Light source unit and vehicle front lamp using the light source unit

ABSTRACT

A light source unit including: a first light source module; a second light source module; and a light source arrangement portion between the first light source module and the second light source module. The first light source module and the second light source module are staggered in at least one of a front-and-back direction and a left-and-right direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/285,310 filed on May 22, 2014, which claims priority of JapanesePatent Application Nos. 2013-116443, 2013-116446, 2013-116447,2013-116444, and 2013-116445, each filed on May 31, 2013. The entiredisclosure of each of the above-identified applications, including thespecification, drawings and claims is incorporated herein by referencein its entirety.

TECHNICAL FIELD

The present application relates to a light source unit and a vehiclefront lamp using the light source unit.

BACKGROUND ART

Vehicles, such as two-wheeled vehicles (motorbikes) or four-wheeledvehicles, are equipped with a vehicle front lamp, such as a headlamp,for forward illumination of the road and such. Halogen bulb lamps, HIDlamps, etc. are conventionally used as the light source in the vehiclefront lamp.

Recent years have seen aggressive progress in the development ofproducts in which semiconductor light-emitting elements such as lightemitting diodes (LEDs) are used as light sources. LEDs are also beingconsidered as a light source for vehicle front lamps due to theirluminous efficiency, which exceeds that of HID lamps, as well as theirlong lifespan.

For example, a vehicle front lamp using LEDs that includes an LEDmodule, a drive circuit that controls driving of the LED module, and aheat dissipating component that dissipates heat generated by the LEDmodule has been proposed. Additionally, a vehicle front lamp using twoLED modules that includes both low beam (passing beam) and high beam(driving beam) functions has also been proposed.

An LED itself generates heat as a result of emitting light, and thisheat causes the temperature of the LED to increase and the light outputof the LED to decrease. Moreover, an LED malfunctions at a relativelylow 150 to 175 degrees Celsius. Additionally, when the intended use isin a vehicle, the temperature of the surrounding area in which thevehicle front lamp is used is a high 125 degrees Celsius, whichtranslates into an allowed increase in temperature of only 25 to 50degrees Celsius. As such, when LEDs are used as the light source in avehicle front lamp, it is necessary to effectively dissipate the heatgenerated by the LEDs. Particularly when two LED modules are used, it isnecessary to dissipate heat even more effectively.

Consequently, with conventional vehicle front lamps, provision of alarge heat sink (heat dissipating component) is common, leading to anincrease in the size and weight of the vehicle front lamp (front lampASSY) and thus an increase in cost.

In light of the above, vehicle front lamps that aim to favorablydissipate heat from the LED and the drive circuit have been proposed.For example, Japanese Unexamined Patent Application Publication No.2013-030371 discloses a vehicle front lamp including a heat dissipatingcomponent (heat sink) having an extending portion that extends forward,an LED module for low beam use arranged on the top surface of theextending portion, an LED module for high beam use arranged on thebottom surface of the extending portion, a reflector that reflects lightemitted from the two LED modules forward, and a drive circuit thatcontrols driving of the two LED modules.

The vehicle front lamp disclosed in Japanese Unexamined PatentApplication Publication No. 2013-030371, further includes a shade forforming the cut-off line for the low beam. The shade is attached to aleading end portion of the extending portion.

In another example, Japanese Unexamined Patent Application PublicationNo. 2007-207528 discloses a vehicle front lamp including first andsecond LED units, first and second reflectors, and a light source standthat supports the first and second LED units. In this vehicle frontlamp, the first LED unit is fixed to the light source stand with a firstclip, and the second LED unit is fixed to the light source stand with asecond clip.

SUMMARY

Technical Problem

A problem with the vehicle front lamp disclosed in Japanese UnexaminedPatent Application Publication No. 2013-030371 is that the vehicle frontlamp is long in the depthwise direction, resulting in a heavy heat sink.

One aspect of the present invention was conceived to solve theabove-described problem and has a first goal to provide a light sourceunit and a vehicle front lamp that is shorter in the depthwisedirection.

Another problem with the vehicle front lamp disclosed in JapaneseUnexamined Patent Application Publication No. 2013-030371 is that thecut-off line is blurry, whereby a desired beam pattern cannot beobtained.

One aspect of the present invention has a second goal to provide a lightsource unit and a vehicle front lamp that achieves a desired beampattern.

Yet another problem with the vehicle front lamp disclosed in JapaneseUnexamined Patent Application Publication No. 2013-030371 is that theheat generated by each the two LED modules affects the other. Inparticular, when the two LED modules emit light simultaneously, the heatgenerated by each of the two LED modules affects the light-emittingstate of the other, leading to the problem of a decreased output oflight.

One aspect of the present invention has a third goal to provide a lightsource unit and a vehicle front lamp that reduces the effect heatgenerated by each of the two light source modules has on the other.

Moreover, with the vehicle front lamp disclosed in Japanese UnexaminedPatent Application Publication No. 2013-030371, since the drive circuitis provided in front of the heat sink (on the LED module side), there isa problem that the drive circuit is easily affected by the heatgenerated by the LED module. In particular, since the vehicle front lampis hermetically sealed and thereby substantially absent of air flow,when the drive circuit is arranged in front of the heat sink (in otherwords, when the drive circuit is internally enclosed), there is aproblem that heat generated by the drive circuit cannot easily escape.

Furthermore, when the drive circuit is provided on the front side of theheat sink, there is a problem that the heat sink is long in thedepthwise direction and the heat sink is heavy.

One aspect of the present invention has a fourth goal to provide a lightsource unit and a vehicle front lamp having a heat sink that is short inthe depthwise direction and minimizes the effect heat from the lightsource module has on the drive circuit.

Moreover, with the vehicle front lamp disclosed in Japanese UnexaminedPatent Application Publication No. 2007-207528, since the two LED units(light source modules) are fixed in place individually, there is aproblem that two fixing components and steps for fixing the LED units inplace are required.

One aspect of the present invention has a fifth goal to provide a lightsource unit and a vehicle front lamp with which two light source modulecan be easily fixed in place.

Solution to Problem

In order to achieve the above-described first goal, a first light sourceunit according to one aspect of the present invention includes: a lightsource module; a heat sink including a light source arrangement portionon which the light source module is arranged and a concave portionopened to surround the light source arrangement portion; and a reflectorwhich includes a through-hole through which the light source arrangementportion is inserted and reflects light emitted from the light sourcemodule. The reflector is arranged having at least a portion thereoflocated in the concave portion.

Moreover, in the first light source unit according to one aspect of thepresent invention, the reflector and the concave portion may have a voidtherebetween.

Moreover, in the first light source unit according to one aspect of thepresent invention, the void may permit air to flow therethrough.

Moreover, in the first light source unit according to one aspect of thepresent invention, one of the reflector and the concave portion mayinclude a protruding portion abutting an other of the reflector and theconcave portion.

Moreover, in the first light source unit according to one aspect of thepresent invention, the other of the reflector and the concave portionmay include a sunken portion at an abutment location of the protrudingportion.

In order to achieve the above-described second goal, a second lightsource unit according to one aspect of the present invention includes: aheat sink including a light source arrangement portion; a first lightsource module and a second light source module arranged sandwiching thelight source arrangement portion; a reflector which reflects lightemitted from the first light source module and the second light sourcemodule; and a light-blocking component that blocks a portion of thelight emitted from at least one of the first light source module and thesecond light source module and reflected off the reflector, thelight-blocking component blocking the portion of the light to form twopredetermined types of beam patterns. The light-blocking component has asurface that reduces light reflection.

Moreover, in the second light source unit according to one aspect of thepresent invention, the light source arrangement portion may be formed asa portion of the heat sink extending therefrom, and the light-blockingcomponent may be attached to the light source arrangement portion andpositioned in front of the first light source module and the secondlight source module.

Moreover, in the second light source unit according to one aspect of thepresent invention, the surface of the light-blocking component may be adark color.

Moreover, in the second light source unit according to one aspect of thepresent invention, the surface of the light-blocking component may beblack.

Moreover, in the second light source unit according to one aspect of thepresent invention, the surface of the light-blocking component may bedeglossed.

Moreover, in the second light source unit according to one aspect of thepresent invention, the light-blocking component may be made of anonmetallic material.

In this case, the nonmetallic material may be resin.

Moreover, in the second light source unit according to one aspect of thepresent invention, the first light source module and the second lightsource module may be arranged sandwiching the light source arrangementportion from above and below. The light-blocking component may include(i) a central portion connected to a front end portion of the lightsource arrangement portion and (ii) a pair of side portions located onrespective sides of the central portion and extending in aleft-and-right direction toward the reflector. The central portion mayhave a front surface having a vertical width greater than a verticalwidth of a front surface of each of the pair of side portions.

In this case, the central portion may include an extension portionextending rearward from an upper end portion and a lower end portion ofthe central portion.

Furthermore, in the second light source unit according to one aspect ofthe present invention, the light-blocking component may include alight-blocking wall covering a side of the first light source module anda side of the second light source module.

Moreover, in the second light source unit according to one aspect of thepresent invention, the reflector may have an upper end portion thatextends forward beyond the light-blocking component.

Moreover, in the second light source unit according to one aspect of thepresent invention, the light-blocking component may include a protrudingrail at a portion connecting with the light source arrangement portion,the light source arrangement portion may include a groove that receivesthe protruding rail, and by fitting the protruding rail and the groovetogether, the light-blocking component may be slidably insertable intothe light source arrangement portion.

Moreover, in the second light source unit according to one aspect of thepresent invention, the first light source module and the second lightsource module may be staggered in at least one of a front-and-backdirection and a left-and-right direction.

Moreover, in the second light source unit according to one aspect of thepresent invention, the two predetermined types of beam patterns may be ahigh-beam beam pattern and a low-beam beam pattern.

In order to achieve the above-described third goal, a third light sourceunit according to one aspect of the present invention includes: a heatsink including a light source arrangement portion; a first light sourcemodule and a second light source module arranged sandwiching the lightsource arrangement portion; and a reflector which reflects light emittedfrom the first light source module and the second light source module.The light source arrangement portion includes a gap in a portionsandwiched by the first light source module and the second light sourcemodule.

Moreover, in the third light source unit according to one aspect of thepresent invention, the first light source module and the second lightsource module may be arranged sandwiching the light source arrangementportion from above and below, and the gap may be formed by dividing aportion of the light source arrangement portion into upper and lowerportions.

Moreover, in the third light source unit according to one aspect of thepresent invention, the light source arrangement portion may include afirst light source arrangement portion on which the first light sourcemodule is arranged, a second light source arrangement portion on whichthe second light source module is arranged, and a joining portionjoining the first light source arrangement portion and the second lightsource arrangement portion.

Moreover, in the third light source unit according to one aspect of thepresent invention, the joining portion may join the first light sourcearrangement portion and the second light source arrangement portion inrearward portions thereof.

Moreover, in the third light source unit according to one aspect of thepresent invention, the light source arrangement portion may be formed asa portion of the heat sink extending therefrom.

Moreover, in the third light source unit according to one aspect of thepresent invention, the first light source module and the second lightsource module may be staggered in either one of a front-and-backdirection and a left-and-right direction.

Moreover, the third light source unit according to one aspect of thepresent invention may further include a light-blocking component thatblocks a portion of the light emitted from at least one of the firstlight source module and the second light source module and reflected offthe reflector. A portion of the light-blocking component is inserted inthe gap.

Moreover, in the third light source unit according to one aspect of thepresent invention, at least one of the first light source module and thesecond light source module may be inclined toward the reflector.

In order to achieve the above-described fourth goal, a fourth lightsource unit according to one aspect of the present invention includes: alight source module; a light source arrangement portion on which thelight source module is arranged; a heat sink including a plurality ofheat dissipation fins that are plate-shaped and arranged in a firstdirection such that main surfaces thereof face each other; a drivecircuit for controlling driving of the light source module; and acircuit cover having the drive circuit arranged therein. The lightsource arrangement portion is provided on a front side of the heat sink,the plurality of heat dissipation fins are provided on a back side ofthe heat sink, and the circuit cover is attached to the plurality ofheat dissipation fins such that at least two ventilation holes arepresent in a spatial region framed by adjacent ones of the plurality ofheat dissipation fins and the circuit cover.

Moreover, in the fourth light source unit according to one aspect of thepresent invention, the at least two ventilation holes may be present ina direction intersecting the first direction.

Moreover, in the fourth light source unit according to one aspect of thepresent invention, the first direction may be a horizontal direction,one of the at least two ventilation holes may be present in an upperportion of the spatial region, and an other of the at least twoventilation holes may be present in a lower portion of the spatialregion.

Moreover, in the fourth light source unit according to one aspect of thepresent invention, the circuit cover may include an open portion, andthe open portion may face the plurality of heat dissipation fins.

Moreover, in the fourth light source unit according to one aspect of thepresent invention, the drive circuit may include a circuit substratehaving a circuit element mounted thereon, the circuit cover may includea base portion and a side wall portion surrounding the base portion, andthe circuit substrate may be arranged on the base portion.

Moreover, in the fourth light source unit according to one aspect of thepresent invention, the plurality of heat dissipation fins may include agroove in a rearward end portion, and the side wall portion may befitted in the groove.

Moreover, in the fourth light source unit according to one aspect of thepresent invention, the side wall portion may be made up of a pluralityof side panels surrounding the base portion, and a gap may be present ina meeting point between adjacent ones of the plurality of side panels.

Moreover, the fourth light source unit according to one aspect of thepresent invention may further include a ventilation hole located betweenthe side wall portion and an outermost one of the plurality of heatdissipation fins and communicating with the spatial region.

In order to achieve the above-described fifth goal, a fifth light sourceunit according to one aspect of the present invention includes: a heatsink including a light source arrangement portion; a first light sourcemodule and a second light source module arranged sandwiching the lightsource arrangement portion; and a clamping component that clamps thefirst light source module and the second light source module to thelight source arrangement portion.

Moreover, in the fifth light source unit according to one aspect of thepresent invention, the clamping component may include a first holdingportion that holds the first light source module down on the lightsource arrangement portion, a second holding portion that holds thesecond light source module down on the light source arrangement portion,and a joining portion joining the first holding portion and the secondholding portion.

Moreover, in the fifth light source unit according to one aspect of thepresent invention, the light source arrangement portion may be formed asa portion of the heat sink extending therefrom, the heat sink mayinclude an insertion hole for insertion of the clamping component, thefirst holding portion and the second holding portion may be insertedthrough the insertion hole, and the joining portion may face a rearwardend portion of the light source arrangement portion.

Moreover, in the fifth light source unit according to one aspect of thepresent invention, the first light source module and the second lightsource module may be simultaneously fixed to the light sourcearrangement portion by pushing the clamping component forward via theinsertion hole.

Moreover, the fifth light source unit according to one aspect of thepresent invention may further include a fixing component for fixingtogether the joining portion and the rearward end portion of the lightsource arrangement portion.

Moreover, in the fifth light source unit according to one aspect of thepresent invention, the first holding portion may be folded back ontoitself at a leading end portion thereof and the second holding portionmay be folded back onto itself at a leading end portion thereof.

Moreover, in the fifth light source unit according to one aspect of thepresent invention, the clamping component may be a flat spring.

Moreover, in the fifth light source unit according to one aspect of thepresent invention, the first light source module and the second lightsource module may each include a light-emitting unit and a substrate onwhich the light-emitting unit is mounted, and the clamping component mayclamp the substrate of the first light source module and the substrateof the second light source module.

Moreover, the fifth light source unit according to one aspect of thepresent invention may further include a reflector that reflects thelight emitted from the light source module. The light source arrangementportion may be formed as a portion of the heat sink extending therefrom,and the reflector may include a through-hole through which the lightsource arrangement portion is inserted.

Moreover, a fifth vehicle front lamp according to one aspect of thepresent invention includes the third light source unit according to anyone of the above aspects, a housing for attaching the fifth light sourceunit, and an optical component arranged in front of the third lightsource unit.

A sixth light source unit according to an aspect of the presentinvention includes: a first light source module; a second light sourcemodule; and a light source arrangement portion between the first lightsource module and the second light source module. The first light sourcemodule and the second light source module are staggered in at least oneof a front-and-back direction and a left-and-right direction.

Moreover, in the sixth light source according to one aspect of thepresent invention, the first light source module is positioned furtherforward than the second light source module.

Moreover, in the sixth light source according to one aspect of thepresent invention, the first light source module is a low-beamlight-emitting diode (LED) module, and the second light source module isa high-beam LED module.

Moreover, in the sixth light source according to one aspect of thepresent invention, a reflector that reflects light from the first lightsource module and the second light source module; and a light-blockingcomponent that blocks a portion of the light emitted from at least oneof the first light source module and the second light source module andreflected off the reflector, the light-blocking component blocking theportion of the light to form two predetermined types of beam patterns.The light-blocking component has a surface that reduces lightreflection.

Moreover, in the sixth light source according to one aspect of thepresent invention, the surface of the light-blocking component isdeglossed.

Moreover, in the sixth light source according to one aspect of thepresent invention, a reflection rate of visible light on the surface ofthe light-blocking component is at least less than a reflection rate ofvisible light on the reflector.

Moreover, in the sixth light source according to one aspect of thepresent invention, a surface roughness Ra of the light-blockingcomponent is at least 0.5 μm.

Moreover, in the sixth light source according to one aspect of thepresent invention, a heat sink is further included, wherein the lightsource arrangement portion is formed as a portion of the heat sinkextending therefrom, and the light-blocking component is attached to thelight source arrangement portion and positioned in front of the firstlight source module and the second light source module.

Moreover, a vehicle front lamp according to one aspect of the presentinvention includes the light source unit according to any of the abovefirst through sixth aspects, a housing for attaching the light sourceunit, and an optical component arranged in front of the light sourceunit.

Advantageous Effects

With the first light source unit according to an aspect of the presentinvention, it is possible to achieve a light source unit having a shortlength in the depthwise direction.

With the second light source unit according to an aspect of the presentinvention, it is possible to achieve a desired beam pattern with a lightsource unit including two light source modules.

With the third light source unit according to an aspect of the presentinvention, it is possible to reduce the effect heat generated by each ofthe two light source modules has on the other.

With the fourth light source unit according to an aspect of the presentinvention, it is possible to shorten the length of the heat sink in thedepthwise direction while reducing the effect heat from the light sourcemodule has on the drive circuit.

With the fifth light source unit according to an aspect of the presentinvention, the two light source module can easily be fixed to the heatsink.

BRIEF DESCRIPTION OF DRAWINGS

The figures depict one or more implementations in accordance with thepresent teaching, by way of example only, no by way of limitations. Inthe figures, like reference numerals refer to the same or similarelements.

FIG. 1A is a perspective view of the front of the light source unitaccording to an embodiment of the present invention from above.

FIG. 1B is a perspective view of the back of the light source unitaccording to an embodiment of the present invention from above.

FIG. 2(a) is a front view of the light source unit according to anembodiment of the present invention, FIG. 2(b) is a top view of the samelight source unit, FIG. 2(c) is a bottom view of the same light sourceunit, FIG. 2(d) is a left side view of the same light source unit, andFIG. 2(e) is a right side view of the same light source unit.

FIG. 3 is an exploded perspective view of the light source unitaccording to an embodiment of the present invention.

FIG. 4A is a cross-sectional perspective view of the front of the lightsource unit according to an embodiment of the present invention fromabove.

FIG. 4B is a cross-sectional view of the light source unit according toan embodiment of the present invention when FIG. 4A is viewed from theside.

FIG. 5 is a perspective view of the light source unit according to anembodiment of the present invention with the reflector and thelight-blocking component removed.

FIG. 6 is a perspective view of the first light source module in thelight source unit according to an embodiment of the present invention.

FIG. 7 is a perspective view from behind of the reflector in the lightsource unit according to an embodiment of the present invention.

FIG. 8A is a perspective view of the front of the heat sink in the lightsource unit according to an embodiment of the present invention.

FIG. 8B is a perspective view of the back of the heat sink in the lightsource unit according to an embodiment of the present invention.

FIG. 9 is a perspective view of the light-blocking component in thelight source unit according to an embodiment of the present invention.

FIG. 10 illustrates the region of the light source module in the lightsource unit according to an embodiment of the present invention thatcannot be seen directly.

FIG. 11 is a simulation of natural convection in the area surroundingthe light source unit according to an embodiment of the presentinvention.

FIG. 12A is a cross-sectional view illustrating light ray paths when thelow beam is used in the light source unit according to a comparativeexample.

FIG. 12B is a cross-sectional view illustrating light ray paths when thelow beam is used in the light source unit according to an embodiment ofthe present invention.

FIG. 13 illustrates the beam pattern of the low beam in the light sourceunit according to a comparative example and an embodiment of the presentinvention, and specifically FIG. 13(a 1) illustrates the distribution oflight on the road with the light source unit according to thecomparative example, FIG. 13(a 2) illustrates the vertical illuminanceof the light source unit according to the comparative example, FIG. 13(b1) illustrates the distribution of light on the road with the lightsource unit 1 according to the embodiment, and FIG. 13(b 2) illustratesthe vertical illuminance of the light source unit according to theembodiment.

FIG. 14 is a simulation of the heat distribution in the vicinity of thelight source component of the light source unit according to anembodiment of the present invention.

FIG. 15 a cross-sectional view of a modified example of the holddownspring in the light source unit according to an embodiment of thepresent invention.

FIG. 16A is a perspective view of the light source unit according to thefirst modified embodiment of the present invention.

FIG. 16B is a perspective view of the light source unit according to thefirst modified embodiment of the present invention.

FIG. 17A is for illustrating the ray paths of light emitted from thefirst light source module in the light source unit according to anembodiment of the present invention.

FIG. 17B is for illustrating the ray paths of light emitted from thefirst light source module in the light source unit according to thefirst modified embodiment of the present invention.

FIG. 17C is for illustrating the ray paths of light emitted from thefirst light source module in the light source unit according to thefirst modified embodiment of the present invention.

FIG. 18A is a perspective view of the front of the light source unitaccording to the second modified embodiment of the present inventionfrom above.

FIG. 18B is a perspective view of the back of the light source unitaccording to the second modified embodiment of the present inventionfrom above.

FIG. 19(a) is a front view of the light source unit according to thesecond modified embodiment of the present invention, FIG. 19(b) is a topview of the same light source unit, FIG. 19(c) is a bottom view of thesame light source unit, FIG. 19(d) is a left side view of the same lightsource unit, and FIG. 19(e) is a right side view of the same lightsource unit.

FIG. 20A is a perspective view of the light-blocking component in thelight source unit according to the second modified embodiment of thepresent invention.

FIG. 20B is a perspective view of the light-blocking component in thelight source unit according to the second modified embodiment of thepresent invention.

FIGS. 21(a)-21(e) illustrate the light source unit according to thesecond modified embodiment of the present invention at various angles.

FIG. 22 is a simplified cross-sectional view of the vehicle front lampaccording to an embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, an illumination light source and a lighting apparatusaccording to exemplary embodiments of the present invention aredescribed with reference to the Drawings. It should be noted that eachof the subsequently-described embodiments show one specific preferredexample of the present invention. The numerical values, shapes,materials, structural components, the arrangement and connection of thestructural components, steps, order of the steps etc. shown in thefollowing exemplary embodiments are mere examples, and are not intendedto limit the scope of the present invention. As such, among thestructural components in the following exemplary embodiments, componentsnot recited in any one of the independent claims which indicate thebroadest concepts of the present invention are described as arbitrarystructural components.

Moreover, in the present specification, “forward” is the direction inwhich light is emitted from the light source unit (light emissiondirection), and “rearward” is the direction opposite “forward”. Itshould be noted that, unless otherwise noted, “left”, “right”, “up”, and“down” refer to directions when the light source unit is viewed from thefront. Moreover, the up-and-down direction is the vertical direction,and the front-and-back direction is, among horizontal directions, theaxis direction of the light source unit, and the left-and-rightdirection is, among horizontal directions, a direction perpendicular toboth the vertical direction and the front-and-back direction.

It should be noted that the respective figures are schematic diagramsand are not necessarily precise illustrations. Additionally, componentsthat are essentially the same share the same reference numerals in therespective figures, and overlapping explanations thereof are omitted orsimplified.

(Overall Structure of the Light Source Unit)

First, the general structure of the light source unit 1 according to anembodiment of the present invention will be described with reference toFIG. 1A, FIG. 1B, FIG. 2, and FIG. 3. FIG. 1A is a perspective view ofthe front of the light source unit according to an embodiment of thepresent invention from above, and FIG. 1B is a perspective view of theback of the same light source unit from above. FIG. 2 illustrates thestructure of the light source unit according to an embodiment of thepresent invention, where (a) is a front view, (b) is a top view, (c) isa bottom view, (d) is a left side view, and (e) is a right side view.FIG. 3 is an exploded perspective view of the light source unitaccording to an embodiment of the present invention.

The light source unit 1 according to the embodiment of the presentinvention is, for example, a light source unit used in a vehicle frontlamp, such as a headlamp. As is illustrated in FIG. 1A, FIG. 1B, andFIG. 2, the light source unit 1 includes a first light source module 10,a second light source module 20, a reflector 30, a heat sink 40, and alight-blocking component 50. The light source unit 1 further includes aholddown spring 60, a drive circuit 70, and a circuit cover 80.

The light source unit 1 according to the embodiment is angular, and asis illustrated in (a) in FIG. 2, has mounting angle dimension of, forexample, 85 mm. Moreover, as is illustrated in (e) in FIG. 2, thedepthwise dimension (length in the depthwise direction) of the lightsource unit 1 is, for example, 65 mm.

Next, the structural components and connection of the structuralcomponents in the light source unit 1 according to the embodiment willbe described in detail using FIG. 4A, FIG. 4B, and FIG. 5, withreference to FIG. 1A through FIG. 3. FIG. 4A is a cross-sectionalperspective view of the front of the light source unit according to anembodiment of the present invention from above, and FIG. 4B is across-sectional view of the same light source unit when FIG. 4A isviewed from the side. FIG. 5 is a perspective view of the light sourceunit according to an embodiment of the present invention with thereflector and the light-blocking component removed.

(Light Source Module)

The first light source module 10 and the second light source module 20constitute the light source component of the light source unit 1. Thefirst light source module 10 is an LED module for low beam use, which isa passing beam, and emits light to illuminate a near portion of the roadahead. On the other hand, the second light source module 20 is an LEDmodule for high beam use, which is a driving beam, and emits light toilluminate a far portion of the road ahead.

In the embodiment, the light-emitting state of the first light sourcemodule 10 and the second light source module 20 can be selectivelyswitched according to a selection made by the user (driver of thevehicle), and either one of the first light source module 10 or thesecond light source module 20 emits light based on a signal (power) fromthe drive circuit 70 according to the selection made by the user. Itshould be noted that a configuration in which both the first lightsource module 10 and the second light source module 20 emit light at thesame time instead of one or the other of the first light source module10 and the second light source module 20 is also acceptable.

As is illustrated in FIG. 4A, FIG. 4B, and FIG. 5, the first lightsource module 10 and the second light source module 20 are arranged on alight source arrangement portion 41 of the heat sink 40 so as tosandwich the light source arrangement portion 41 from above and below.More specifically, the first light source module 10 is fixed to the topsurface of the light source arrangement portion 41 of the heat sink 40with the light-emitting surface facing upward. The second light sourcemodule 20 is fixed to the bottom surface of the light source arrangementportion 41 with the light-emitting surface facing downward. Although notshown in the Drawings, it should be noted that the first light sourcemodule 10 and the second light source module 20 are arranged on thelight source arrangement portion 41 with heat transfer materialtherebetween. This allows the heat generated by the first light sourcemodule 10 and the second light source module 20 to be effectivelytransferred to the heat sink 40 (light source arrangement portion 41).

Moreover, in the embodiment, the first light source module 10 and thesecond light source module 20 are arranged staggered in thefront-and-back direction. More specifically, the first light sourcemodule 10 is positioned further forward than the second light sourcemodule 20. This makes it possible to reduce the length in the depthwisedirection (front-and-back length) of the light source unit 1.

In other words, since the desired light distribution pattern of the lowbeam and the high beam is different, the positional relationship of thefirst light source module 10 and the second light source module 20relative to the reflective surface of the reflector 30 is different. Assuch, if the positions of the first light source module 10 and thesecond light source module 20 in the front-and-back direction were to bemade the same, the front-and-back length of the light source unit 1would increase. For this reason, in the embodiment, the first lightsource module 10 and the second light source module 20 are arrangedstaggered in the front-and-back direction. This allows for thefront-and-back length of the light source unit 1 to be shortened.Consequently, a compact, light-weight light source unit 1 can beachieved. The first light source module 10 and the second light sourcemodule 20 are staggered (the distance from the end of one substrate tothe end of the other substrate in the front-and-back direction) by, forexample, 5.0 mm to 20.0 mm.

It should be noted that the first light source module 10 and the secondlight source module 20 may be staggered in the left-and-right directioninstead of the front-and-back direction. Even in this case, thefront-and-back length of the light source unit 1 can be shortened.Moreover, the first light source module 10 and the second light sourcemodule 20 may be staggered in any of the left-and-right andfront-and-back directions.

Next, the structure of the first light source module 10 and the secondlight source module 20 will be described in detail using FIG. 6. FIG. 6is a perspective view of the first light source module in the lightsource unit according to an embodiment of the present invention. Itshould be noted that the first light source module 10 and the secondlight source module 20 have the same structure, and as such, hereinafteronly the structure of the first light source module 10 will bedescribed.

As is illustrated in FIG. 6, the first light source module 10 is an LEDunit (an LED package) which uses an LED, and includes a substrate 11 anda light-emitting apparatus (light-emitting unit) 12 arranged on thesubstrate 11.

The substrate 11 includes: a metal heat transfer plate (heat spreader)for transferring heat from the light-emitting apparatus 12 to the heatsink 40; and a wiring substrate arranged on the heat transfer plate. Thewiring substrate includes an insulating substrate material made of resinand metal wiring and electrode pads formed in a predetermined pattern onthe insulating substrate material etc. Moreover, an insulating layer isformed on the surface of the insulating substrate material so as toexpose the electrode pads. A highly reflective white resist, forexample, can be used as the insulating film.

As is illustrated in FIG. 6, it should be noted that two of theelectrode pads 11 a are provided, and each electrode pads 11 a iselectrically connected to an LED chip on the light-emitting apparatus 12via metal wiring (not shown in the Drawings) and a bonding wire 11 b.The electrode pad 11 a is a connection terminal that receives directcurrent power for causing the light-emitting apparatus 12 to emit light,and is connected to a lead wire drawn from the drive circuit 70. Forexample, a high voltage side (plus side) lead wire is connected to oneof the two electrode pads 11 a, and a low voltage side (minus side) leadwire is connected to the other of the two electrode pads 11 a.

The light-emitting apparatus 12 is a light-emitting unit having an LEDas the light source, and is mounted on the substrate 11. Thelight-emitting apparatus 12 is, for example, an LED module having a chipon board (COB) structure in which LED chips (bare chips) are directlymounted on a mounting substrate. The light-emitting apparatus 12includes a mounting substrate 12 a, an LED 12 b mounted on the mountingsubstrate 12 a, and a sealing material (not shown in the Drawings) whichseals the LED 12 b.

The mounting substrate 12 a is a sub-mount arranged on the substrate 11,and is a substrate for mounting the LED 12 b. For example, a ceramicsubstrate made from aluminum oxide (alumina) or aluminum nitride, forexample, a metal-based substrate made from metal with a resin coatedlayer, or a resin substrate made from resin can be used as the mountingsubstrate 12 a.

A plurality of LEDs 12 b are mounted on the mounting substrate 12 a.Each LED 12 b is a bare chip which emits a monochromatic visible lightand is die-bonded on the mounting substrate 12 a with a die touchmaterial (die bond material). A blue LED chip which emits a blue lightwhen power passes through it can be used as the LED 12 b (bare chip).The blue LED chip is a gallium nitride semiconductor light-emittingelement having a central wavelength of 400 nm to 480 nm, formed of ann-type gallium nitride compound semiconductor layer, a light-emittinglayer formed from a gallium nitride compound semiconductor containingindium, and a p-type gallium nitride compound semiconductor layerstacked in this order on a sapphire substrate. The chip size of the LEDchip is, for example, about 1 mm squared with a thickness of roughly 100μm, but the chip size is not limited to this example.

The sealing material is formed on the mounting substrate 12 a so as toseal the plurality of LEDs 12 b (for example, all of the LEDs 12 b) onthe mounting substrate 12 a collectively. It should be noted that thesealing material may be formed to seal each of the LEDs 12 bindividually.

The sealing material is mainly made from a translucent material, butwhen it is necessary to convert the wavelength of the light emitted fromthe LEDs 12 b into a predetermined wavelength, a wavelength convertingmaterial is mixed into the translucent material. The sealing materialaccording to the embodiment includes a phosphor as the wavelengthconverting material, and is a wavelength converting component whichconverts the wavelength (color) of the light emitted from the LEDs 12 b.

Silicon resin, for example, can be used as the translucent resinmaterial in the sealing material. It should be noted that thetranslucent resin material is not limited to silicon resin; afluorocarbon polymer, hybrid resin of silicon resin and epoxy resin, ora urea resin, for example, can be used.

When, for example, blue LEDs which emit a blue light are used as theLEDs 12 b, yttrium aluminum garnet (YAG) yellow phosphor particles, forexample, can be used as the phosphor particles contained in the sealingmaterial in order to yield a white light. With this, a portion of theblue light emitted from the LEDs 12 b is wavelength-transformed into ayellow light by the yellow phosphor particles included in the sealingmaterial. Then, the blue light not absorbed by the yellow phosphorparticles mixes with the yellow light resulting from thewavelength-transformation by the yellow phosphor particles so that thelight emitted from the sealing material is white. Alternatively, thesealing material can be dispersed with a light diffusing material suchas silica particles. The yellow phosphor particles are not limited toYAG phosphor particles; for example, silicate phosphor particles,nitride phosphor particles, oxynitride phosphor particles, sialonphosphor particles, or sulfide phosphor particles can be used.

It should be noted that the wavelength converting material can beprovided as a separate material from the sealing material, and provideddirectly or indirectly on the outside of the sealing material.

(Reflector)

The reflector 30 is a reflecting component that reflects light emittedfrom the first light source module 10 and the second light source module20. The front surface (reflective surface) of the reflector 30 is shapedso as to reflect, in a predetermined direction, the light emitted fromthe first light source module 10 and the second light source module 20.

In this case, the shape of the reflective surface may be altered toinclude a first reflecting portion (upper portion) 31 that reflects thelight emitted from the first light source module 10 and a secondreflecting portion (lower portion) 32 that reflects the light emittedfrom the second light source module 20. This makes it possible to form adesired beam pattern for each of the low beam and the high beam.Moreover, the shape of the reflective surface may be altered such thatthe first reflecting portion 31 and the second reflecting portion 32 areprovided on left and right portions, respectively. This makes itpossible to make the left-and-right symmetry of the beam pattern aboutthe optical axis unsymmetrical.

Moreover, the first reflecting portion 31 and the second reflectingportion 32 may be configured as separate components and arranged suchthat the reflective surfaces are non-contiguous. However, in theembodiment, the first reflecting portion 31 and the second reflectingportion 32 are integrally formed, whereby the reflective surface of thefirst reflecting portion 31 and the reflective surface of the secondreflecting portion 32 are contiguous. In other words, the reflector 30is a single component. Forming the first reflecting portion 31 and thesecond reflecting portion 32 as a single component eliminates the needto form them individually, thereby reducing the man-hours required toassemble the reflector.

The reflector 30 configured in this manner can be manufactured by, forexample, forming a mirror surface by metal vapor deposition (forexample, aluminum vapor deposition) on the surface of a heat-resistantresin.

As is illustrated in FIG. 3, FIG. 4A, and FIG. 4B, the reflector 30according to the embodiment is a substantially bowl-shaped(substantially dome-shaped) reflective plate (reflective mirror) havinga front surface functioning as a reflective surface that is sunken in.In other words, the reflector 30 has a curved surface protrudingrearward. The reflector 30 is arranged having at least a portion thereoflocated in a concave portion 42 of the heat sink 40. In other words, atleast a portion of the reflector 30 is present in the space framed bythe concave portion 42.

Moreover, as is illustrated in FIG. 7, the substantially central portionof the reflector 30 is provided with a through-hole 33 through which thelight source arrangement portion 41 of the heat sink 40 is inserted.FIG. 7 is a perspective view from behind of the reflector in the lightsource unit according to an embodiment of the present invention.

When fixing the reflector 30 and the heat sink 40 together, thereflector 30 and the heat sink 40 are arranged in place by inserting thelight source arrangement portion 41 through the through-hole 33 andbringing the back surface of the reflector 30 and the inner surface ofthe concave portion 42 of the heat sink 40 near each other, as isillustrated in FIG. 4B.

At this time, the reflector 30 is arranged such that the back surface ofthe reflector 30 and the front surface of the heat sink 40 (the innersurface of the concave portion 42) are separated such that a gap (void)is present between the back surface of the reflector 30 and the frontsurface of the heat sink 40.

Moreover, as is illustrated in FIG. 7, two protruding portions 34 whichcontact the heat sink 40 are provided on the back surface of thereflector 30.

More specifically, the protruding portion 34 contacts the bottom surfaceof a sunken portion 42 a formed in the inner surface of the concaveportion 42 of the heat sink 40, as is illustrated in FIG. 4B. Theprotruding portion 34 coming into contact with the bottom surface of thesunken portion 42 a determines the relative positioning of the reflector30 and the heat sink 40. As such, the distance of the gap between thereflector 30 and the heat sink 40 can be set according to the height ofthe protruding portion 34. In other words, provision of the protrudingportion 34 makes it easy to determine the relative positioning of thereflector 30 and the heat sink 40 with a high degree of accuracy.

Moreover, in the embodiment, the first light source module 10 and thesecond light source module 20 are fixed to the heat sink 40 (the lightsource arrangement portion 41). With this, the protruding portion 34makes it easy to determine not only the relative positioning of thereflector 30 and the heat sink 40 with a high degree of accuracy, butthe relative positioning of, with respect to the heat sink 40, (i) thefirst light source module 10 and the second light source module 20 and(ii) the reflector 30 easily and with a high degree of accuracy as well.

As is illustrated in FIG. 7, a screw hole 34 a is provided in theprotruding portion 34. As is illustrated in FIG. 4B, while theprotruding portion 34 is abutting the sunken portion 42, a reflectorscrew 92 is inserted through the through-hole 42 b in the sunken portion42 a from behind the heat sink 40 and screwed into the screw hole 34 ain the protruding portion 34. This makes it possible to fix thereflector 30 and the heat sink 40 together.

(Heat Sink)

The heat sink 40 is a heat dissipating component for dissipating heatgenerated by the first light source module 10 and the second lightsource module 20 to the outside (to the atmosphere). As such, the heatsink 40 is preferably formed using a material having a high rate of heattransfer, such as metal. The heat sink 40 is, for example, an aluminumdie cast of an aluminum composite metal, such as Al—Si—Fe (HT-1) orAl—Si—CU (ADC12), for example. It should be noted that in theembodiment, the front surface of the heat sink 40 is treated withalumite.

Next, a detailed description of the structure of the heat sink 40 willbe given using FIG. 8A and FIG. 8B. FIG. 8A is a perspective view of thefront of the heat sink in the light source unit according to anembodiment of the present invention, and FIG. 8B is a perspective viewof the back of the same heat sink.

As is illustrated in FIG. 8A and FIG. 8B, the heat sink 40 includes alight source arrangement portion 41, a concave portion 42 opened tosurround the light source arrangement portion 41, and a heat dissipatingportion 43 provided on the back surface side of (behind) the concaveportion 42.

The light source arrangement portion 41 is a portion for arranging thefirst light source module 10 and the second light source module 20, andis formed extending out from a portion of the heat sink 40. The lightsource arrangement portion 41 according to the embodiment is provided onthe front surface side (in front) of the concave portion 42 and extendsforward from the substantially central portion (the portion sunken thedeepest) of the concave portion 42. It should be noted that the lightsource arrangement portion 41 according to the embodiment is providedextending beyond the inner portion of the concave portion 42. In otherwords, when the heat sink 40 is viewed from the side, the front endportion of the light source arrangement portion 41 can be seen.

Moreover, a portion of the light source arrangement portion 41 isdivided into upper and lower portions. In the embodiment, the lightsource arrangement portion 41 is split into two portions—upper andlower—that project from the base portion on the concave portion 42 sidetoward the front. The light source arrangement portion 41 includes: afirst light source arrangement portion 41 a and a second light sourcearrangement portion 41 b divided with a gap (void) therebetween; and ajoining portion 41 c joining the first light source arrangement portion41 a and a second light source arrangement portion 41 b.

More specifically, the substantially flat-plate-shaped first lightsource arrangement portion 41 a and the substantially flat-plate-shapedsecond light source arrangement portion 41 b are provided with apredetermined gap (void) therebetween in the vertical direction, and thefirst light source arrangement portion 41 a and the second light sourcearrangement portion 41 b are connected together in a rearward portion bythe joining portion 41 c. With this, grooves 41 d and 41 e formed by thegap between the first light source arrangement portion 41 a and thesecond light source arrangement portion 41 b are formed in thefrontward, left side, and right side surfaces of the light sourcearrangement portion 41.

The groove 41 d is formed in the frontward surface of the light sourcearrangement portion 41, and when the light source arrangement portion 41is viewed from the front, extends from one of the left-and-right edgesof the light source arrangement portion 41 to the other. The groove 41 eis formed in the right and left side surfaces of the light sourcearrangement portion 41, and when the light source arrangement portion 41is viewed from the side, extends from the frontward edge of the lightsource arrangement portion 41 to the joining portion 41 c.

Moreover, as is illustrated in FIG. 4A, FIG. 4B, and FIG. 5, the gapbetween the first light source arrangement portion 41 a and the secondlight source arrangement portion 41 b is directly below the first lightsource module 10 and directly above the second light source module 20.In other words, the gap is provided in the light source arrangementportion 41 between the first light source module 10 and the second lightsource module 20.

More specifically, the gap defined by the first light source arrangementportion 41 a and the second light source arrangement portion 41 bextends in the horizontal direction, and the region in which the gap ispresent is greater than the region sandwiched by the first light sourcemodule 10 (substrate) and the second light source module 20 (substrate).

With this configuration, since the gap between the first light sourcearrangement portion 41 a and the second light source arrangement portion41 b functions as a heat-insulating barrier of air, it is possible toreduce the effect heat generated by each of the first light sourcemodule 10 and the second light source module 20 has on the other. Forexample, it is possible to reduce the transfer of heat generated by oneof the first light source module 10 and the second light source module20 to the other. This makes it possible to achieve a compact,light-weight light source unit 1 since it is possible to arrange thefirst light source module 10 and the second light source module 20 to becloser together. Moreover, since the effect heat has on each other canbe reduced, the lifespan of the first light source module 10 and thesecond light source module 20 can be increased. In particular, thisadvantageous effect is great when the first light source module 10 andthe second light source module 20 emit light at the same time, since thetemperature increases evenly due to the respectively generated heat.

In the embodiment, the distance of the gap defined by the first lightsource arrangement portion 41 a and the second light source arrangementportion 41 b (the distance of the gap in the portion of the light sourcearrangement portion 41 sandwiched by the first light source module 10and the second light source module 20) is preferably within the range0.5 mm to 2.0 mm. When the gap is less than 0.5 mm, there is apossibility that the gap will close in the case of, for example,physical impact. On the other hand, when the gap is greater than 2.0 mm,it is difficult to make the size of the light source unit 1 compact.Moreover, it is further preferable that the gap be within a range of 1.0mm to 1.5 mm. This makes it easier to insert, for example, a portion ofthe light-blocking component 50 in the gap.

Furthermore, as is illustrated in FIG. 8A, an indention 41 a 1 forplacement of the first light source module 10 is provided in the firstlight source arrangement portion 41 a. Moreover, in accordance with theprovision of the indention 41 a 1, two protrusions 41 a 2 are providedon the first light source arrangement portion 41 a. The protrusion 41 a2 functions as a stopper for the substrate 11 of the first light sourcemodule 10, and the end portion of the substrate 11 contacts theprotrusion 41 a 2. In this way, positioning of the first light sourcemodule 10 is restricted by the first light source module 10 being placedin the indention 41 a 1.

Similarly, an indention 41 b 1 for placement of the second light sourcemodule 20 is provided in the second light source arrangement portion 41b, and in accordance with the provision of the indention 41 b 1, twoprotrusions 41 b 2 are provided on the second light source arrangementportion 41 b. The protrusion 41 b 2 is also a stopper and is in contactwith the substrate of the second light source module 20. In this way,positioning of the second light source module 20 is restricted by thesecond light source module 20 being placed in the indention 41 b 1.

Moreover, as is illustrated in FIG. 8B, a screw hole 41 c 1 is providedin the rearward surface of the joining portion 41 c. As is illustratedin FIG. 4B, a holddown spring screw 91 inserted from behind through athrough-hole 63 a in the holddown spring 60 held down in the rearwardportion of the light source arrangement portion 41 is screwed in thescrew hole 41 c 1.

As is illustrated in FIG. 4A and FIG. 4B, the concave portion 42 isformed so as to correspond to the shape of the reflector 30. The concaveportion 42 in the embodiment curves in a rearward direction, and theshape of the inner surface is formed to have the outer surface shape of,substantially, a hemisphere. In this way, the inner surface of theconcave portion 42 is a concave surface.

As is illustrated in FIG. 4B and FIG. 8A, two sunken portions 42 a thatcorrespond to the two protruding portions 34 of the reflector 30 areprovided in the concave portion 42. A bottom surface that abuts theprotruding portion 34 is formed in the sunken portion 42 a. Moreover,the through-hole 42 b passing through the heat sink 40 in thefront-and-back direction is provided in the sunken portion 42 a. Uponfixing the reflector 30 and the heat sink 40 together, the reflectorscrew 92 is inserted through the through-hole 42 b from the back of theconcave portion 42.

Moreover, an insertion hole 42 c is provided in the concave portion 42.The insertion hole 42 c is formed for the holddown spring 60 to beinserted into. More specifically, as is illustrated in FIG. 8B, a singleopening is formed in the back surface side of the concave portion 42,and two openings are formed on the front surface side of the concaveportion 42 on the top surface and bottom surface sides of the lightsource arrangement portion 41 for insertion of a first holding portion61 and a second holding portion 62. It should be noted that a lead wireelectrically connecting the first light source module 10 and the secondlight source module 20 to the drive circuit 70 is also inserted in theinsertion hole 42 c.

The heat sink 40 is configured such that at least a portion of thereflector 30 is positioned inside the concave portion 42 when thereflector 30 and the heat sink 40 are fixed together. With thisconfiguration, the length of the light source unit in the depthwisedirection can be made to be shorter than conventional vehicle frontlamps.

The heat dissipating portion 43 is the main heat dissipating portion ofthe heat sink 40, and dissipates heat transferred from the heat sink 40to the outside. It should be noted that in the heat sink 40, heat isdissipated in regions other than the heat dissipating portion 43 aswell.

As is illustrated in FIG. 4A, FIG. 4B, and FIG. 8B, the heat dissipatingportion 43 includes heat dissipation fins 43 a. Provision of the heatdissipation fins 43 a in this manner allows for the contact area withair to be increased while at the same time saving surface area of theheat dissipating portion 43, and as such, heat can be efficientlydissipated by the heat sink 40.

The heat dissipation fins 43 a extend in the vertical direction(up-and-down direction) and are made up of a plurality of plate-shapedcomponents. In other words, the plurality of plate-shaped heatdissipation fins 43 a each stand vertically from the back surface of theconcave portion 42 and are lined up in the left-and-right direction.

The heat dissipation fins 43 a other than the outermost heat dissipationfins 43 a in the left-and-right direction are formed on the back surfaceof the concave portion 42 bulging rearward, but the rearward ends ofthese heat dissipation fins 43 a are formed to be flush with each other.In other words, the width (height) of the heat dissipation fins 43 afrom the top down changes from wide, to narrow, to wide again. Moreover,the outermost heat dissipation fins 43 a in the left-and-right directionform the outline of the heat dissipating portion 43 and are exposed suchthat the outer surfaces thereof can be seen from the outside, even afterattachment of the circuit cover 80 to the heat sink 40.

A groove 43 a 1 is provided in a rearward end portion of each of theplurality of heat dissipation fins 43 a other than the outermost heatdissipation fins 43 a in the left-and-right direction. An end portion ofa top wall 82 a of the circuit cover 80 is fitted in the groove 43 a 1.With this, the positioning of the circuit cover 80 in the up-and-downdirection relative to the heat sink 40 is restricted.

It should be noted that a notch 43 a 2 is provided in a bottom endportion of the heat dissipation fin 43 a. A bottom wall 82 b of thecircuit cover 80 latches onto the notch 43 a 2.

Moreover, as is illustrated in FIG. 1A, FIG. 1B, and FIG. 2, innersurfaces of clasps 82 c 1 and 82 d 1 provided on a right wall 82 c and aleft wall 82 d, respectively, of the circuit cover 80 abut the outersurfaces of the outermost heat dissipation fins 43 a in theleft-and-right direction. With this, the positioning of the circuitcover 80 in the left-and-right direction relative to the heat sink 40 isrestricted. It should be noted that a through-hole 43 a 3 is provided oneach of the outermost heat dissipation fins 43 a in the left-and-rightdirection. Protrusions 82 c 2 and 82 d 2 provided on the right wall 82 cand the left wall 82 d, respectively, of the circuit cover 80 catch onthe through-holes 43 a 3 so as to clasp thereto. This makes it possibleto fix the heat sink 40 and the circuit cover 80 together.

As is illustrated in FIG. 8A, an attachment hole 44 is provided in eachof the four corner portions of the heat sink 40. The attachment holes 44are used when the light source unit 1 is attached to the housing of thevehicle front lamp. For example, it is possible to insert screws throughthe attachment holes 44 from either the front or back surface, andattach the light source unit 1 to the housing of the vehicle front lamp.

This configuration makes it possible to easily replace only the lightsource unit 1, thereby reducing the cost of parts in the case ofreplacement. In other words, with existing vehicle front lamps that useLEDs, since the LED light source (light source unit) is larger in sizethan the opening portion of the vehicle front lamp and intricatelyattached, if an abnormality occurs in the LED light source (loss oflight, flickering, reduction of light), the whole vehicle front lampneeds to be replaced. In contrast, with the embodiment, by providingholes or openings in appropriate locations on the vehicle front lampcorresponding to the attachment holes 44, if an abnormality occurs inthe light source unit 1, only the light source unit 1 can easily bereplaced.

Moreover, by attaching the light source unit 1 to the housing of thevehicle front lamp using the attachment holes 44, designing themechanism for aiming or leveling the vehicle front lamp is simple.

It should be noted that, in the embodiment, the diameter of theattachment hole 44 is 5.5 mm, but the diameter is not limited to thisexample. Moreover, the attachment holes 44 are provided in the fourcorner portions of the heat sink 40, but this example is not limiting.It is preferable that the attachment holes 44 be provided on two of thecorner portions.

(Light-Blocking Component)

The light-blocking component 50 is a separator separating the concavespace framed by the reflector 30 and, in order to form two predeterminedbeam patterns (light distribution patterns), blocks the light emittedfrom at least one of the first light source module 10 and the secondlight source module 20 and reflected off the reflector 30. The twopredetermined beam patterns are beam patterns for two beams that travelat different angles, and in the embodiment, are the beam pattern for thehigh beam and the beam pattern for the low beam.

Moreover, the light-blocking component 50 according to the embodimentblocks a portion of light emitted from both the first light sourcemodule 10 and the second light source module 20.

For example, a portion of the light emitted from the first light sourcemodule 10 and traveling downward at an angle after being reflected bythe first reflecting portion (upper portion) 31 of the reflector 30 isblocked by the upper portion of the light-blocking component 50. Thisforms the predetermined pattern for the low beam and the cut-off linefor the low beam.

On the other hand, a portion of the light emitted from the second lightsource module 20 and traveling upward at an angle after being reflectedby the second reflecting portion (lower portion) 32 of the reflector 30is blocked by the lower portion of the light-blocking component 50.

It should be noted that the light-blocking component 50 also blocks aportion of light emitted from both the first light source module 10 andthe second light source module 20 that directly hits the light-blockingcomponent 50.

The light-blocking component 50 is a light-absorbing component thatactively absorbs light, and the surface of the light-blocking component50 is configured to reduce the reflection of light. The reflection rateof visible light on the surface of the light-blocking component 50 is atleast less than the reflection rate of the reflector 30, and thereflection rate of the surface of the light-blocking component 50 canbe, for example, 0.1% to 10.0%.

Moreover, the surface roughness Ra of the light-blocking component 50may be 0.5 μm or more. This makes it easy to make the reflection rate ofthe light-blocking component 50 10% or less. The surface roughness Ra ofthe light-blocking component 50 is preferably 1.0 μm≦Ra≦10.0 μm. Thismakes it possible to more favorably decrease the reflection rate. Evenmore preferably, the reflection rate Ra is 2.0 μm≦Ra≦5.0 μm.

In the embodiment, since the first light source module 10 and the secondlight source module 20 emit white light (visible light), the surface ofthe light-blocking component 50 is black. This makes it possible toreduce the reflection of light by the light-blocking component 50 sincethe surface of the light-blocking component 50 can absorb the whitelight in a satisfactory manner.

For example, when the first light source module 10 is turned on andcaused to emit the low beam, the light arriving at the light-blockingcomponent 50 is absorbed by the light-blocking component 50. This makesit possible to reduce the reflection of light at the light-blockingcomponent 50. As a result, it is possible to reduce glare and achieve adesired beam pattern. Moreover, it is possible to achieve a clearcut-off line.

It should be noted that the color of the surface of the light-blockingcomponent 50 may be a color other than black so long as it absorbs thelight emitted from the first light source module 10 and the second lightsource module 20 in a satisfactory manner and reduces the reflection oflight. For example, the surface of the light-blocking component 50 maybe a dark color such as a shade of brown or grey, and if the color oflight emitted from the first light source module 10 and the second lightsource module 20 is a color other than white, a different color may beused.

Furthermore, the surface of the light-blocking component 50 is treatedwith a low-reflection treatment for minimizing the reflection of light;a treatment in which the surface is deglossed, for example, can be used.In the embodiment, all surfaces of the light-blocking component 50 arematte black. In this way, by deglossing the surface of thelight-blocking component 50, reflection of the light emitted from thefirst light source module 10 and the second light source module 20 offthe light-blocking component 50 can further be reduced. This makes itpossible to more accurately achieve a desired beam pattern.

It should be noted that the surface treatment to reduce the reflectionof light is not limited to a treatment in which the surface isdeglossed; a different low-reflection treatment may be performed. Forexample, the light-blocking component 50 can be coated with ananti-reflection coating, an anti-reflection film can be applied to thelight-blocking component 50, and a chemical conversion treatment, suchas an alumite (anodic oxide film), can be performed on thelight-blocking component 50.

The light-blocking component 50, for example, can be made of anonmetallic material, such as resin. When resin is used as the materialfor the light-blocking component 50, it is preferable that the resin bea high-temperature resin, such as polyphenylene sulfide (PPS), since thelight-blocking component 50 is arranged near the high-temperature firstlight source module 10 and second light source module 20.

Next, a detailed description of the structure of the light-blockingcomponent 50 will be given using FIG. 9. FIG. 9 is a perspective view ofthe light-blocking component in the light source unit according to anembodiment of the present invention.

As is illustrated in FIG. 4A and FIG. 9, the light-blocking component 50includes: a central portion 51 connected to a front end portion of thelight source arrangement portion 41; and a pair of side portions 52located on respective sides of the central portion 51 and extending inthe left-and-right direction toward the reflector 30.

As is illustrated in FIG. 9, the central portion 51 includes: a frontsurface portion 51 a having a front surface that is a planar surfaceextending in the vertical and left-and-right directions and facingforward; and an upper extension portion 51 b and lower extension portion51 c that extend so as to protrude rearward from the upper end portionand the lower end portion of the front surface portion 51 a,respectively.

The width of the front surface of the front surface portion 51 a in thevertical direction is configured to be greater than the width of thefront surface of the pair of side portions 52. Moreover, as isillustrated in FIG. 4B, the height of the front surface portion 51 a ishigher than the height of the first light source module 10. In otherwords, the top edge of the front surface portion 51 a is positionedhigher than the highest part of the first light source module 10.Moreover, the width of the front surface portion 51 a in theleft-and-right direction is greater than the width of the first lightsource module 10. By configuring the front surface of the front surfaceportion 51 a in this way, when viewed from the front, the first lightsource module 10 is covered by the front surface portion 51 a.

Similarly in regard to the second light source module 20, when viewedfrom the front, the second light source module 20 is arranged so as tobe covered by the front surface portion 51 a.

Moreover, the upper extension portion 51 b and the lower extensionportion 51 c extend to a position overlapping the front end portions ofthe substrates 11 of the first light source module 10 and the secondlight source module 20. In the embodiment, since the second light sourcemodule 20 is arranged further back than the first light source module10, the length of the lower extension portion 51 c is longer than thelength of the upper extension portion 51 b.

By configuring the central portion 51 in this way, since the region inwhich the light source component (the first light source module 10 andthe second light source module 20) is directly seen is restricted, it ispossible to reduce being blinded by direct viewing of the light sourcecomponent, as is illustrated in FIG. 10. It should be noted that FIG. 10illustrates the region of the light source module in the light sourceunit according to an embodiment of the present invention that cannot beseen directly.

As is illustrated in FIG. 9, a horizontally long protrusion 51 d thatprotrudes rearward is provided on the rearward surface of the centralportion 51 (on the back surface of the front surface portion 51 a). Theprotrusion 51 d fits in the groove 41 d of the light source arrangementportion 41 upon attaching the light-blocking component 50 to the heatsink 40.

Moreover, the pair of side portions 52 include: a front surface portion52 a having a front surface that is a planar surface extending in thevertical and left-and-right directions and facing forward; an upperextension portion 52 b and lower extension portion 52 c that extendrearward from the upper end portion and the lower end portion of thefront surface portion 52 a, respectively; and an inner surface portion52 d connecting a portion of the upper extension portion 52 b and thelower extension portion 52 c adjacent to the central portion 51.

As is illustrated in FIG. 4A, the upper extension portion 52 b and thelower extension portion 52 c in the side portion 52 extend rearwarduntil contact is made with the reflective surface of the reflector 30,and the rearward edges of the upper extension portion 52 b and the lowerextension portion 52 c adjacent to the reflector have a shapecorresponding to the shape of the reflective surface of the reflector30. With this, the concave spatial region of the reflector 30 iscompletely divided into two—upper and lower—spaces by the side portion52.

Moreover, as is illustrated in FIG. 9, inner surface portions 52 d inthe pair of side portions 52 are provided with protrusions 52 e thatprotrude in the left-and-right direction so as to face each other. Theprotrusion 52 e is a protruding rail extending in the front-and-backdirection, and is provided on the connection portion of thelight-blocking component 50 with the light source arrangement portion41. The protrusion 52 e is fitted in the groove 41 e of the light sourcearrangement portion 41 illustrated in FIG. 5. For example, uponattaching the light-blocking component 50 to the heat sink 40, theprotrusion 52 e (rail) is fitted in the groove 41 e of the light sourcearrangement portion 41 and the light-blocking component 50 is slidablyinserted into the light source arrangement portion 41 in a rearwarddirection. In other words, the groove 41 e is a rail groove configuredto receive the protrusion (rail) 52 e.

With this configuration, the light-blocking component 50 can be fixed tothe light source arrangement portion 41 by pushing so as to slide theprotrusion 52 e of the light-blocking component 50 along the groove 41 eof the light source arrangement portion 41. This makes it possible toboth fix and position the light-blocking component 50 and the heat sink40 at the same time without using, for example, a positioning boss or aseparate fixing component, thereby reducing the size and weight of thelight source unit 1. Furthermore, the light-blocking component 50 can berapidly assembled with accurate and simple positioning.

By fitting the protrusion 52 e of the light-blocking component 50 in thegroove 41 e of the light source arrangement portion 41, the gap betweenthe first light source arrangement portion 41 a and the second lightsource arrangement portion 41 b in the light source arrangement portion41 can be kept from narrowing by, for example, deformation of the firstlight source arrangement portion 41 a or the second light sourcearrangement portion 41 b. With this, the relative positioning of thereflector 30 with the first light source module 10 and the second lightsource module 20 is sustainable.

Moreover, the front surface portion 51 a of the central portion 51extends in the vertical direction, and the vertical width of the frontsurface of the front surface portion 51 a of the central portion 51 isgreater than the vertical direction width of the front surface of thefront surface portion 52 a of the pair side portions 52. It should benoted that the front surface of the front surface portion 51 a of thecentral portion 51 is flush with the front surface of the front surfaceportion 52 a of the pair of side portions 52.

The light-blocking component 50 configured in this way is arrangedfurther forward than the first light source module 10 and the secondlight source module 20 and attached to the light source arrangementportion 41, as is illustrated in FIG. 4A and FIG. 4B. More specifically,the light-blocking component 50 is attached to the light sourcearrangement portion 41 such that the central portion 51 is attached tothe front end surface of the light source arrangement portion 41 and thepair of side portions 52 are attached to the left and right sidesurfaces of the light source arrangement portion 41. At this time, thefront end portion of the light source arrangement portion 41 is arrangedbetween the upper extension portion 51 b and the lower extension portion51 c of the central portion 51.

(Holddown Spring)

As is illustrated in FIG. 4A, FIG. 4B, and FIG. 5, the holddown spring60 is a clamping component (clip) that clamps the first light sourcemodule 10 and the second light source module 20 arranged on the lightsource arrangement portion 41 to the light source arrangement portion41.

The first light source module 10 and the second light source module 20are clamped down by the holddown spring 60 while sandwiching the lightsource arrangement portion 41. With this, the first light source module10 and the second light source module 20 are fixed to the light sourcearrangement portion 41. In other words, the holddown spring 60 is afixing component for simultaneously fixing the first light source module10 and the second light source module 20 to the light source arrangementportion 41. Fixing the first light source module 10 and the second lightsource module 20 with a single fixing component reduces the size andweight of the light source unit 1.

The holddown spring 60 according to the embodiment is a U-shaped flatspring, and as is illustrated in FIG. 3 and FIG. 4B, is configured ofthe plate-shaped first holding portion 61, the plate-shaped secondholding portion 62, and a plate-shaped joining portion 63. The firstholding portion 61 and the second holding portion 62 are spaced apart bya predetermined distance and joined together by the joining portion 63.The joining portion 63 joins one end of the first holding portion 61 toone end of the second holding portion 62.

The joining portion 63 is provided with a through-hole 63 acorresponding to the screw hole 41 c 1 provided in the rearward surfaceof the light source arrangement portion 41. The holddown spring screw 91is inserted in the through-hole 63 a upon fixing the holddown spring 60to the heat sink 40 (light source arrangement portion 41).

This kind of holddown spring 60, which is a flat spring clip, can beformed by, for example, bending a single rectangular metal sheet. Theholddown spring 60 according to the embodiment is formed using 0.8 mmthick SUS304.

(Drive Circuit)

The drive circuit (driver) 70 is a circuit unit that controls driving ofthe first light source module 10 and the second light source module 20.For example, the drive circuit 70 is a light circuit that stablysupplies a predetermined power to the first light source module 10 andthe second light source module 20 and controls flashing of the firstlight source module 10 and the second light source module 20. The drivecircuit 70, for example, supplies direct current power to the firstlight source module 10 and the second light source module 20 to causelight emission by (to turn on) one of the first light source module 10and the second light source module 20. It should be noted that the drivecircuit 70 is arranged inside the circuit cover 80.

As is illustrated in FIG. 3, FIG. 4A, and FIG. 4B, the drive circuit 70includes a circuit substrate (driver substrate) 71 and a plurality ofcircuit elements (not shown in the Drawings) mounted on the circuitsubstrate 71. The plurality of circuit elements constitute an electricalcircuit for controlling the driving of the first light source module 10and the second light source module 20.

The circuit substrate 71 is, for example, a printed substrate (PCBsubstrate) having metal wiring such as copper foil patterned on one mainsurface (soldering surface) thereof. The plurality of circuit elementsare electrically connected together by the metal wiring. A substantiallyrectangular shaped substrate can be used as the circuit substrate 71,but the circuit substrate 71 is not limited to this shape.

In the embodiment, the circuit substrate 71 is fixed to a base portion81 of the circuit cover 80 such that the soldering surface of thecircuit substrate 71 faces the bottom surface of the base portion 81 ofthe circuit cover 80.

The drive circuit 70 (circuit substrate 71), first light source module10, and the second light source module 20 are electrically connected bya plurality of output lead wires (power supply lead wires), for example.For example, a pair of output lead wires for supplying direct currentpower to the first light source module 10 and a pair of output leadwires for supplying direct power to the second light source module 20are fed out from the drive circuit 70 and electrically connected to thefirst light source module 10 and the second light source module 20through the insertion hole 42 c.

It should be noted that the drive circuit 70 is not directly attached tothe heat sink 40, but retained indirectly by the heat sink 40. Morespecifically, the circuit cover 80 housing the drive circuit 70 isattached to the heat dissipating portion 43 of the heat sink 40, and thedrive circuit 70 is attached to the back surface of the heat sink 40 viathe circuit cover 80.

(Circuit Cover)

As is illustrated in FIG. 4A and FIG. 4B, the circuit cover (drivercover) 80 is configured so as to cover the drive circuit 70. The circuitcover 80 according to the embodiment is a circuit case and retains thedrive circuit 70 while housing the drive circuit 70. The circuit cover80 can be made of, for example, metal, but may also be made of resin.

As is illustrated in FIG. 3, the circuit cover 80, for example, isbox-shaped and has an open portion 80 a. The circuit cover 80 includes:the rectangular plate-shaped base portion (base panel) 81 having thecircuit substrate 71 of the drive circuit 70 fixed thereto; and the sidewall portion 82 surrounding the entire perimeter of the base portion 81.

The side wall portion 82 includes four plate-shaped components standingvertically at the four sides of the base portion 81. The side wallportion 82 according to the embodiment includes the top wall (top panel)82 a, the bottom wall (bottom panel) 82 b, the right wall (right panel)82 c, and the left wall (left panel) 82 d. It should be noted that thetop wall 82 a and the bottom wall 82 b are positioned opposite eachother, and the right wall 82 c and the left wall 82 d are positionedopposite each other.

In the embodiment, the adjacent portions (portions of the meetingpoints) of the top wall 82 a, the bottom wall 82 b, the right wall 82 c,and the left wall 82 d are not welded, for example, and are not joinedtogether. With this, a slight gap is present between adjacent portionsof the top wall 82 a, the bottom wall 82 b, the right wall 82 c, and theleft wall 82 d.

Moreover, the right wall 82 c and the left wall 82 d are each providedwith a pair of clasps 82 c 1 and 82 d 1. The clasps 82 c 1 and 82 d 1are each formed by bending a portion of the right wall 82 c and the leftwall 82 d outward twice. The clasps 82 c 1 and 82 d 1 are bent such thatthey contact the outer surface of the outermost heat dissipation fins 43a in the left-and-right direction. With this, the positioning of thecircuit cover 80 and the heat dissipation fins 43 a in theleft-and-right direction is determined, as is illustrated in FIG. 1A andFIG. 1B.

Moreover, as is illustrated in FIG. 3, (d) in FIG. 2, and (e) in FIG. 2,the right wall 82 c and the left wall 82 d are provided with theprotrusions 82 c 2 and 82 d 2, respectively. The protrusions 82 c 2 and82 d 2 latch onto the through-holes 43 a 3 provided in the outermostheat dissipation fins 43 a in the left-and-right direction, as isillustrated in FIG. 1A and FIG. 1B. This makes it possible to fix thecircuit cover 80 to the heat dissipating portion 43. The size of theprotrusions 82 c 2 and 82 d 2 according to the embodiment are roughlythe same as the size of the through-holes 43 a 3, and the protrusions 82c 2 and 82 d 2 are configured to engage the through-holes 43 a 3 fromthe inner side of the heat dissipation fins 43 a.

The circuit cover 80 configured in this way is fixed such that the openportion 80 a faces the heat dissipation fins 43 a and the circuit cover80 covers the back surface of the heat sink 40, as is illustrated inFIG. 1B, FIG. 4A, and FIG. 4B. More specifically, the end portion of thetop wall 82 a engages the groove 43 a 1 in each heat dissipation fin 43a, and the bottom wall 82 b is latched to the notch 43 a 2 of the heatdissipation fins 43 a. Moreover, the protrusions 82 c 2 and 82 d 2 onthe right wall 82 c and the left wall 82 d engage the through-holes 43 a3 in each of the outermost heat dissipation fins 43 a in theleft-and-right direction. This makes it possible to fix the circuitcover 80 to the heat dissipation fins 43 a.

In this way, in the embodiment, the circuit cover 80 retaining the drivecircuit 70 is fixed to the heat dissipation fins 43 a. In other words,the drive circuit 70 and the circuit cover 80 are fixed to the backsurface of the heat sink 40. With this, similar to Japanese UnexaminedPatent Application Publication No. 2013-030371, since the length of theheat sink in the depthwise direction can be reduced, it is possible tokeep the heat sink from becoming heavier, compared to when the drivecircuit is provided on the front surface of the heat sink.

However, in the embodiment, the first light source module 10 and thesecond light source module 20 are fixed to the front surface of the heatsink 40, and moreover, the first light source module 10 and the secondlight source module 20 are electrically connected to the drive circuit70 via a connecting cable such as a lead wire. In other words, thedriver unit (the drive circuit 70 and the circuit cover 80) and thelight source component (the first light source module 10 and the secondlight source module 20) are not separate components, but are attached toa single component (the heat sink 40). This makes it possible to reduceman hours and costs. Moreover, it is possible to reduce the size andweight of the light source unit 1 since a plurality of connection cablesin accordance with the layout are not necessary due to the reduction inthe number of parts.

Moreover, in the embodiment, the open portion 80 a of the circuit cover80 is fixed to the heat dissipation fins 43 a so as to face the heatdissipation fins 43 a.

Moreover, in the embodiment, the end portion of top wall 82 a of thecircuit cover 80 engages the groove 43 a 1 of the heat dissipation fins43 a. This makes it possible to easily fix, to the heat dissipation fins43 a, the circuit cover 80 including the open portion 80 a adjacent tothe heat dissipation fins 43 a. This further makes it possible to easilyrestrict the positioning of the circuit cover 80.

(Light Source Unit Functionality Example)

Next, an example of the functionality of the light source unit 1according to the embodiment will be given.

As described above, with the light source unit 1 according to theembodiment, at least a portion of the reflector 30 is located in theconcave portion 42 of the heat sink 40.

With this configuration, compared to arranging the reflector 30 in aposition on the front side of a heat sink not provided with the concaveportion 42, the length of the heat sink 40 in the depthwise directioncan be reduced. This makes it possible to keep the weight of the heatsink 40 from increasing.

Moreover, with the light source unit 1 according to the embodiment, apredetermined gap (void) is present between the reflector 30 and theconcave portion 42 of the heat sink 40. More specifically, as isillustrated in FIG. 4A and FIG. 4B, the back surface of the reflector 30and the front surface (inner surface) of the concave portion 42 aredistanced so as to have a gap therebetween. Furthermore, this gap is aregion framed by substantially spherical surfaces and is configured toallow outside air to flow through. In the embodiment, the gap is presentalmost throughout the entire region between the back surface of thereflector 30 and the inner surface of the concave portion 42 of the heatsink 40, and the gap acts as a flow passageway whereby air can flowtherethrough in four directions: up, down, left, and right.

With this configuration, as is illustrated in FIG. 11, a passagewaythrough which air can flow by natural convection forms even in the gapbetween the reflector 30 and the heat sink 40. FIG. 11 is a simulationof natural convection in the area surrounding the light source unitaccording to an embodiment of the present invention.

In this way, even if the front surface of the heat sink 40 is covered bythe reflector 30, by providing a gap between the reflector 30 and theheat sink 40, the front surface portion of the heat sink 40—in otherwords, the portion of the heat sink 40 adjacent the light source module(adjacent the heat source)—can be effectively cooled. This makes itpossible to increase the ability of the heat sink 40 to dissipate heat.As a result, it possible to effectively dissipate the heat generated bythe first light source module 10 and the second light source module 20.

It should be noted that in the embodiment, the shape of the innersurface of the concave portion 42 and the shape of the outer surface ofthe reflector 30 are substantially the same, and the gap between theheat sink 40 and the reflector 30 is substantially constant throughout,but this example is not limiting.

Moreover, with the light source unit 1 according to the embodiment, aspatial region S expanding in the up-and-down direction is formedbetween adjacent ones of the heat dissipation fins 43 a, as isillustrated in FIG. 1B and FIG. 4B.

In this case, since a top panel (heat dissipation panel) 43 b isprovided on the upper portion of the heat dissipation fins 43 a so as tostraddle the heat dissipation fins 43 a, the portion directly above thespatial region S is blocked off by the top panel 43 b, but with thelight source unit 1 according to the embodiment, the circuit cover 80 isattached to the heat dissipation fins 43 a such that at least twoventilation holes (openings) are present in the spatial region S framedby adjacent ones of the heat dissipation fins 43 a and the circuit cover80. In the embodiment, the circuit cover 80 is attached to the heatdissipation fins 43 a such that two ventilation holes are present in adirection (vertical direction) intersecting the arrangement direction(left-and-right direction) of the heat dissipation fins 43 a.

More specifically, after the circuit cover 80 is attached to the heatdissipation fins 43 a (the heat sink 40), a major portion of therearward side of the plurality of spatial regions S is blocked off bythe circuit cover 80, but as is illustrated in FIG. 1B, even after thecircuit cover 80 has been attached to the heat sink 40, the upperportion of the rearward side of each spatial region S is provided with afirst ventilation hole (first opening). In other words, with regard tothe upper region of each spatial region S, the portion directly above isclosed off by the top panel 43 b, but the rearward upper portion isopened and a ventilation hole communicating with each spatial region Sis present.

On the other hand, as is illustrated in (c) in FIG. 2 and FIG. 4B, sincethe lower portion of the heat dissipation fins 43 a is not provided withheat dissipation panels, even after the circuit cover 80 has beenattached to the heat sink 40, the lower region of each spatial region Sis opened and a second ventilation hole (second opening) is present.

In this way, in the embodiment, even after the circuit cover 80 has beenattached to the heat sink 40, openings (ventilation holes) which allowfor ventilation in two locations—top and bottom—are provided at thespatial regions S between heat dissipation fins 43 a. In other words, ineach spatial region S, the first ventilation hole is present in theupper region, and the second ventilation hole is present in the lowerregion.

With this configuration, in the spatial region S, it is possible toachieve natural convection of air from the bottom up via the firstventilation hole in the upper region the second ventilation hole in thelower region, as is illustrated in FIG. 11.

With this, even in a configuration in which the back surface of the heatsink 40 is covered by the circuit cover 80, it is possible toeffectively cool the back surface of the heat sink 40 and effectivelydissipate heat transferred to the heat sink 40 to the outside. Thismakes it possible to effectively dissipate the heat generated by thefirst light source module 10 and the second light source module 20.

In this way, with the embodiment, back surface side and front surfaceside portions of the heat sink 40 are cooled by natural convection. Thismakes it possible to effectively dissipate the heat transferred to theheat sink 40. In particular, since the vehicle front lamp ishermetically sealed and thereby substantially absent of air flow, it ispossible to effectively dissipate heat generated by the first lightsource module 10 and the second light source module 20 and heatgenerated by the drive circuit 70 by cooling the heat sink 40 withnatural convection in the manner described above.

It should be noted that in the embodiment, the top panel 43 b isprovided on the upper portion of the heat dissipation fin 43 a, butprovision of the top panel 43 b is not required. By omitting the toppanel 43 b, the ability of the heat sink 40 to dissipate heat improvessince air can flow straight in the vertical direction.

However, by providing the top panel 43 b, it is possible to prevent theuser's finger from entering the gap between adjacent ones of the heatdissipation fins 43 a upon attaching the light source unit 1 to thehousing of the vehicle front lamp. With this, even if the drive circuit70 is present near the heat dissipation fins 43 a such as is the case inthe embodiment, it is possible to prevent the user from touching therecharging portion of the drive circuit 70 when attaching (replacing)the light source unit 1, thereby making attaching the light source unit1 more safe. Furthermore, by providing the top panel 43 b, reduction offoreign matter such as dust or liquid such as water or oil dropletsentering the driver unit (the drive circuit 70 and the circuit cover 80)can also be achieved. This makes it possible to achieve a reliable lightsource unit.

Moreover, in the embodiment, the plate-shaped plurality of heatdissipation fins 43 a extending in the vertical direction are arrangedin the left-and-right direction, but they may be arranged in anydirection. For example, plate-shaped plurality of heat dissipation fins43 a extending in the left-and-right direction may be arranged in thevertical direction.

However, since heat rises, by providing plate-shaped plurality of heatdissipation fins 43 a extending in the vertical direction (up-and-downdirection) are arranged in the left-and-right direction, such as is thecase in the embodiment, it is possible realize a more smooth flow of airdue to natural convection.

Moreover, with the light source unit 1 according to the embodiment, theopen portion 80 a of the circuit cover 80 is fixed to the heatdissipation fins 43 a so as to face the heat dissipation fins 43 a. Withthis, as is illustrated in FIG. 4B, the spatial region S formed by theheat dissipation fins 43 a and the region surrounding the drive circuit70 can be spatially coupled, and the spatial region framed by the heatdissipation fins 43 a and the circuit cover 80 can be enlarged.

With this, air can easily circulate by natural convection through theopenings in the upper region and the lower region of the spatial regionS, and the cooling efficiency of the heat sink 40 and the drive circuit70 can be increased.

Furthermore, with the light source unit 1 according to the embodiment,as described above, the circuit substrate 71 is fixed to a base portion81 of the circuit cover 80 such that the soldering surface of thecircuit substrate 71 faces the bottom surface of the base portion 81 ofthe circuit cover 80. In other words, the circuit substrate 71 isarranged such that the surface (the component mounting surface) on theopposite side of the soldering surface faces the heat sink 40. Moreover,in the embodiment, molded resin for covering the entire circuit elementis not formed in the circuit cover 80.

With this, it is possible to make a natural convection occur easily inthe spatial region between the heat sink 40 (heat dissipation fins 43 a)and the circuit cover 80 (drive circuit 70), and possible to directlycool the circuit element with air cooling since the circuit element canbe exposed to the air in the spatial region. As such, it is possible toeffectively dissipate heat generated by the circuit element via thespatial region S and effectively dissipate heat generated by the drivecircuit 70.

Moreover, with the light source unit 1 according to the embodiment, asis illustrated in FIG. 1B, even after the circuit cover 80 is fixed tothe heat dissipation fins 43 a, ventilation holes (openings)communicating with the spatial region S are present between therightmost heat dissipation fin 43 a and the right wall 82 c and betweenthe left-most heat dissipation fin 43 a the left wall 82 d.

With this, it is possible for air to flow in and out through theventilation holes (openings) as well, so it is possible to make anatural convection occur easily in the spatial region S.

Moreover, as described above, with the light source unit 1 according tothe embodiment, the portions of the meeting points of the four walls ofthe side wall portion 82 are not joined together, and a slight gap ispresent at the meeting points between adjacent ones of the top wall 82a, the bottom wall 82 b, the right wall 82 c, and the left wall 82 d.

With this, the gap functions as a ventilation hole, and air can flow inand out of this gap. As such, it is possible to make natural convectionoccur even more easily in the spatial region S.

Moreover, with the light source unit 1 according to the embodiment, theopening (ventilation hole) 82 b 1 is formed in the bottom wall 82 b, asis illustrated in (c) in FIG. 2 and FIG. 3.

This makes it possible to cool the drive circuit 70 since air can flowin through the opening 82 b 1. In particular, with the embodiment, as isdescribed above, the spatial region S formed by the heat dissipationfins 43 a and the region surrounding the drive circuit 70 are spatiallycoupled, and the upper portion of the spatial region S is opened toallow air to flow by natural convection. This makes it possible toeffectively cool the drive circuit 70 since air flows in through theopening 82 b 1.

(Light Source Unit Second Functionality Example)

Next, a second example of the functionality of the light source unit 1according to the embodiment will be given in detail, along with thedevelopments that resulted in the present invention, using FIG. 12A,FIG. 12B, and FIG. 13.

FIG. 12A is a cross-sectional view illustrating light ray paths when thelow beam is used in the light source unit according to a comparativeexample. FIG. 12B is a cross-sectional view illustrating light ray pathswhen the low beam is used in the light source unit according to anembodiment of the present invention. FIG. 13 illustrates the beampattern of the low beam in the light source unit according to acomparative example and an embodiment of the present invention. Morespecifically, in FIG. 13, (a1) illustrates the distribution of light onthe road with the light source unit according to the comparativeexample, (a2) illustrates the vertical illuminance of the light sourceunit according to the comparative example, (b1) illustrates thedistribution of light on the road with the light source unit 1 accordingto the embodiment, and (b2) illustrates the vertical illuminance of thelight source unit according to the embodiment. It should be noted thatonly a cross-section of the light distribution is illustrated in FIG.12A and FIG. 12B. The distribution in the depthwise direction (verticaldirection on paper) is not illustrated.

The light source unit 1000 according to the comparative exampleillustrated in FIG. 12A is the light source unit 1 according to theembodiment when the surface of the light-blocking component is amirrored surface, and includes a light-blocking component 500 treated tohave a mirrored surface. Moreover, each beam pattern in FIG. 13indicates the low-beam beam pattern when the light source unit isinstalled in an automobile headlamp (vehicle front lamp). As such, thereflector has a shape that darkens the right side of the beam pattern toprevent glare for oncoming traffic (in other words, the illumination onthe side of oncoming traffic is low) and illuminates the right side tomake pedestrians easy to see. Moreover, (a1) and (b1) illustrate beampatterns when the road is illuminated, as seen from above, and (a2) and(b2) illustrate beam patterns when a wall is illuminated.

As is illustrated in (a1) in FIG. 13, it was found that with the lightsource unit 1000 according to the comparative example, unwanted light isgenerated relative to the desired pattern, causing glare for oncomingtraffic. Moreover, as is illustrated in (a2) in FIG. 13, it was foundthat areas that should be dark are actually illuminated, causing thecut-off line to appear blurry. In this way, it was found that a desiredbeam pattern cannot be obtained with the light source unit 1000according to the comparative example. In particular, it was found that adesired beam pattern cannot be obtained with the low beam, on whichcut-off line adjustment is performed.

As a result of diligent examination on the part of the inventors, thelight-blocking component 500 treated to have a mirrored surface, whichwas believed to be effective, was found to be the cause of theabove-described problem. In other words, it was found that the lightreflected by the light-blocking component 500 are not effective beams,but rather appeared as null beams (unwanted light; light having anadverse effect). For example, as is illustrated in FIG. 12A, it wasfound that light arriving at the light-blocking component 500 isreflected when the low beam is used in the light source unit 1000according to the comparative example.

The present invention has been conceived, based on this underlyingknowledge, to achieve a desired beam pattern by reducing the reflectionof light off the surface of the light-blocking component in light sourcemodule.

As such, in the embodiment, the surface of the light-blocking component50 is configured to reduce reflection of light. More specifically, thesurface of the light-blocking component 50 is black, which is a colorcapable of efficiently absorbing white light. With this, the lightemitted from the first light source module 10 and the second lightsource module 20 that arrives at the light-blocking component 50 can beabsorbed by the surface of the light-blocking component 50, therebyreducing the reflection of light.

For example, as is illustrated in FIG. 12B, when the low beam is used inthe light source unit 1 according to the embodiment, the light arrivingat the light-blocking component 50 is absorbed by the light-blockingcomponent 50, making it possible to reduce the reflection of light.

As a result, it is possible to reduce the generation of unwanted lightand reduce glare for oncoming traffic, as is illustrated in (b1) in FIG.13. Moreover, it is possible to achieve a clear cut-off line since theareas that should be dark are actually dark, as is illustrated in (b2)in FIG. 13. In this way, with the light source unit 1 according to theembodiment, it is possible to achieve a desired beam pattern. Inparticular, it is possible to achieve a desired beam pattern with thelow beam.

Furthermore, in the embodiment, the light-blocking component 50 istreated to degloss the surface thereof.

This makes it possible to further reduce the reflection of light off thesurface of the light-blocking component 50, thereby achieving a highlyaccurate desired beam pattern.

Moreover, in the embodiment, the front surface of the central portion 51(the front surface portion 51 a) of the light-blocking component 50 hasa vertical width that is greater than the vertical width of the frontsurface of the side portion 52, and when viewed from the front, thefirst light source module 10 and the second light source module 20 arecovered by the central portion 51 (the front surface portion 51 a).

With this configuration, since the region in which the light sourcecomponent (the first light source module 10 and the second light sourcemodule 20) is directly seen is restricted, it is possible to reducebeing blinded by direct viewing of the light source component, as isillustrated in FIG. 10.

Furthermore, in the embodiment, an extension portion (the upperextension portion 51 b and lower extension portion 51 c) extendingrearward is provided on the central portion 51 of the light-blockingcomponent 50, as is illustrated in FIG. 4B.

With this configuration, since the region in which the light sourcecomponent (the first light source module 10 and the second light sourcemodule 20) is directly seen, not only from the front but from an angleas well, is restricted, it is possible to reduce blinding by directviewing of the light source component even further.

Moreover, in the embodiment, the groove 41 e is formed in the sidesurface of the light source arrangement portion 41 of the heat sink 40,as is illustrated in FIG. 8A. Additionally, the protrusion 52 efunctioning as a protruding rail is formed on the inner surface portion52 d of the side portion 52 of the light-blocking component 50, as isillustrated in FIG. 9. With this, by fitting the protrusion 52 e and thegroove 41 e together, the light-blocking component 50 is slidablyinsertable into the light source arrangement portion 41.

With this configuration, the light-blocking component 50 can be fixed tothe light source arrangement portion 41 by pushing so as to slide theprotrusion 52 e of the light-blocking component 50 along the groove 41 eof the light source arrangement portion 41. This makes it possible toboth fix and position the light-blocking component 50 and the heat sink40 at the same time without using, for example, a positioning boss or aseparate fixing component, thereby reducing the size and weight of thelight source unit 1. Furthermore, the light-blocking component 50 can berapidly assembled with accurate and simple positioning.

By fitting the protrusion 52 e of the light-blocking component 50 in thegroove 41 e of the light source arrangement portion 41, the gap betweenthe first light source arrangement portion 41 a and the second lightsource arrangement portion 41 b in the light source arrangement portion41 can be kept from narrowing by, for example, deformation of the firstlight source arrangement portion 41 a or the second light sourcearrangement portion 41 b. With this, the relative positioning of thereflector 30 with the first light source module 10 and the second lightsource module 20 is sustainable.

(Light Source Unit Third Functionality Example)

Next, a third example of the functionality of the light source unit 1according to the embodiment will be given.

With the light source unit 1 according to the embodiment, the portion ofthe light source arrangement portion 41 of the heat sink 40 between thefirst light source module 10 and the second light source module 20 has agap of a predetermined length. More specifically, as is illustrated inFIG. 4A, FIG. 4B, and FIG. 5, a gap is provided between the first lightsource arrangement portion 41 a and the second light source arrangementportion 41 b of the light source arrangement portion 41, and the gap isdirectly below the first light source module 10 and directly above thesecond light source module 20.

Moreover, the gap defined by the first light source arrangement portion41 a and the second light source arrangement portion 41 b extends in thehorizontal direction, and the region in which the gap is present isgreater than the region sandwiched by the first light source module 10(substrate) and the second light source module 20 (substrate).

With this configuration, since the gap between the first light sourcearrangement portion 41 a and the second light source arrangement portion41 b functions as a heat-insulating barrier of air, it is possible toreduce the effect heat generated by each of the first light sourcemodule 10 and the second light source module 20 has on the other. Forexample, it is possible to reduce the transfer of heat generated by oneof the first light source module 10 and the second light source module20 to the other.

This makes it possible to achieve a compact, light-weight light sourceunit 1 since it is possible to arrange the first light source module 10and the second light source module 20 to be closer together. Moreover,since the effect heat has on each other can be reduced, the lifespan ofthe first light source module 10 and the second light source module 20can be increased.

In particular, when the first light source module 10 and the secondlight source module 20 emit light at the same time, the temperatureincreases evenly due to the respectively generated heat, and so thisadvantageous effect is great.

In the embodiment, the distance of the gap defined by the first lightsource arrangement portion 41 a and the second light source arrangementportion 41 b (the distance of the gap in the portion of the light sourcearrangement portion 41 sandwiched by the first light source module 10and the second light source module 20) is preferably within the range0.5 mm to 2.0 mm. When the gap is less than 0.5 mm, there is apossibility that the gap will close in the case of, for example,physical impact. On the other hand, when the gap is greater than 2.0 mm,it is difficult to make the size of the light source unit 1 compact.Moreover, it is further preferable that the gap be within a range of 1.0mm to 1.5 mm. This makes it easier to insert, for example, a portion ofthe light-blocking component 50 in the gap.

Moreover, in the embodiment, the groove 41 d is provided in the frontend portion of the light source arrangement portion 41. In other words,the first light source arrangement portion 41 a and the second lightsource arrangement portion 41 b are joined together in the rearwardportion by the joining portion 41 c, and are not joined together in thefrontward portion.

With this, it is possible to reduce the generation of a pool of heatforming in the front end portion of the light source arrangement portion41, and possible to effectively draw heat generated by the first lightsource module 10 and the second light source module 20 rearward with thefirst light source arrangement portion 41 a and the second light sourcearrangement portion 41 b.

Next, a description of the heat distribution in the vicinity of thelight source component of the light source unit 1 according to theembodiment will be given using FIG. 14. FIG. 14 is a simulation of theheat distribution in the vicinity of the light source component of thelight source unit according to an embodiment of the present invention.It should be noted that FIG. 14 illustrates the heat distribution whenonly the first light source module 10 is caused to emit light.

As is illustrated in FIG. 14, the heat generated by the first lightsource module 10 is transferred to the rearward portion of the heat sink40. Moreover, as can be seen from the heat distribution in the lightsource arrangement portion 41 illustrated in FIG. 14, although the heatgenerated by the first light source module 10 is transferred to both thefirst light source arrangement portion 41 a and the second light sourcearrangement portion 42 b, the heat is transferred more to the rearwardportion of the first light source arrangement portion 41 a than therearward portion of the second light source arrangement portion 42 b. Inother words, this shows that it is possible to reduce the effect heatgenerated by the first light source module 10 has on the second lightsource module 20.

(Light Source Unit Fourth Functionality Example)

Next, a fourth example of the functionality of the light source unit 1according to the embodiment will be given.

The heat sink 40 according to the embodiment includes the light sourcearrangement portion 41 on the front surface side and the heatdissipating portion 43 (heat dissipation fins 43 a) on the back surfaceside. Furthermore, the circuit cover 80 having the drive circuit 70arranged therein is attached to the rearward side of the heatdissipation fins 43 a. In this way, with the light source unit 1according to the embodiment, the light source component (the first lightsource module 10 and the second light source module 20) is arranged onthe front surface side of the heat sink 40, and the drive circuit 70 isprovided on the back surface side of the heat sink 40.

This allows the drive circuit 70 to be relatively unaffected by the heatgenerated by the light source component (the first light source module10 and the second light source module 20). Moreover, the length of theheat sink 40 in the depthwise direction can be reduced by providing thedrive circuit 70 on the back surface side of the heat sink 40, wherebythe weight of the heat sink 40 can be kept from increasing.

Moreover, the heat dissipation fins 43 a are constituted of a pluralityof plate-shaped components arranged along the first direction such thatthe main surfaces thereof face each other. The heat dissipation fins 43a according to the embodiment are arranged along the left-and-rightdirection. With this, as is illustrated in FIG. 4B, a spatial region Sexpanding in the up-and-down direction is formed between adjacent onesof the heat dissipation fins 43 a.

With the light source unit 1 according to the embodiment, it is possibleto increase the ability of the heat sink 40 to dissipate heat due to thecirculation of air in the surrounding region of the heat dissipationfins 43 a, and thus reduce the effect the heat from the light sourcecomponent (the first light source module 10 and the second light sourcemodule 20) has on the drive circuit 70 and reduce the depthwisedimension length of the heat sink 40.

(Light Source Unit Fifth Functionality Example)

Next, a fifth example of the functionality of the light source unit 1according to the embodiment will be given.

When fixing the first light source module 10 and the second light sourcemodule 20 to the light source arrangement portion 41 using the holddownspring 60, the holddown spring 60 is inserted through the insertion hole42 c of the concave portion 42 from behind the concave portion 42 of theheat sink 40, and clamps down the first light source module 10 and thesecond light source module 20, as is illustrated in FIG. 4B.

More specifically, the joining portion 63 is made to face the rearwardend portion of the light source arrangement portion 41, and each of thefirst holding portion 61 and the second holding portion 62 are insertedthrough respective ones of two insertion holes 42 c. The holddown spring60 is pushed forward while the first holding portion 61 is in contactwith the surface of the substrate 11 of the first light source module 10and the second holding portion 62 is in contact with the surface of thesubstrate 11 of the second light source module 20.

At this time, the elastic force from insertion of the first light sourcemodule 10 and the second light source module 20 between the firstholding portion 61 and the second holding portion 62 applies a pressingforce to the first light source module 10 and the second light sourcemodule 20. For example, by making the gap between the first holdingportion 61 and the second holding portion 62 smaller than the gapbetween the surface of the substrate of the first light source module 10and the surface of the substrate of the second light source module 20,the gap between the first holding portion 61 and the second holdingportion 62 widens when the holddown spring 60 sandwiches the first lightsource module 10 and the second light source module 20. At this time,the spring returning force of the holddown spring 60 applies a pressingforce to the first light source module 10 and the second light sourcemodule 20. With this, the substrate 11 of the first light source module10 is held down on the light source arrangement portion 41 by the firstholding portion 61. Similarly, the substrate 11 of the second lightsource module 20 is held down on the light source arrangement portion 41by the second holding portion 62.

Moreover, when the holddown spring 60 is pushed forward (pushed towardthe front end portion side of the light source arrangement portion 41),the pushing of the holddown spring 60 in a forward direction applies aforce acting to move the first light source module 10 and the secondlight source module 20 forward, but the protrusions 41 a 2 and 41 b 2(see FIG. 5) provided on the light source arrangement portion 41function as stoppers keeping the first light source module 10 and thesecond light source module 20 from moving forward.

With this, only the holddown spring 60 moves forward in such a mannerthat the first holding portion 61 and the second holding portion 62glide over the surfaces of the substrates 11 of the first light sourcemodule 10 and the second light source module 20. As a result, the firstlight source module 10 and the second light source module 20 are pusheddown on the light source arrangement portion 41 by the holddown spring60 and thereby fixed to the light source arrangement portion 41. Inother words, the pushing down force by the holddown spring 60 makes itpossible to restrict the positions of the first light source module 10and the second light source module 20.

Moreover, after the holddown spring 60 is pushed until the joiningportion 63 abuts the rearward surface of the light source arrangementportion 41, the holddown spring screw (fixing component) 91 is insertedthrough the through-hole 63 a from behind and screwed into the screwhole 41 c 1 provided in the back surface of the light source arrangementportion 41. This makes it possible to fix the holddown spring 60 and thelight source arrangement portion 41 together with a screw.

It should be noted that in the embodiment, since the first light sourcemodule 10 is arranged to be positioned more forward than the secondlight source module 20, the length of the first holding portion 61 islonger than the length of the second holding portion.

In this way, with the light source unit 1 according to the embodiment,the first light source module 10 and the second light source module 20can be simultaneously fixed to the light source arrangement portion 41with a single holddown spring 60.

This makes it possible to reduce the number of fixing components sincethere is no need to individually fix the first light source module 10and the second light source module 20 with separate fixing components.Moreover, it is possible to reduce the number of steps for fixing thefirst light source module 10 and the second light source module 20 tothe heat sink 40, thereby simplifying the process.

It should be noted that in the embodiment, the holddown spring 60 isfixed to the light source arrangement portion 41 with the holddownspring screw 91, but the holddown spring screw 91 is not required to beused. In other words, the holddown spring 60 may be fixed to the lightsource arrangement portion 41 with only the elastic force of theholddown spring 60. However, using the holddown spring screw 91 to fixthe holddown spring 60 to the light source arrangement portion 41 allowsfor the holddown spring 60 to be more securely fixed to the light sourcearrangement portion 41, thereby preventing separation of the holddownspring 60.

Moreover, the shape of the holddown spring 60 is not limited to theexample illustrated in FIG. 3. For example, a holddown spring 60A havingthe shape illustrated in FIG. 15 may be used. The holddown spring 60Aillustrated in FIG. 15 includes a folded back portion 61 a and a foldedback portion 62 a. The folded back portion 61 a is formed by foldingback the leading end portion of the first holding portion 61 inward, andthe folded back portion 62 a is formed by folding back the leading endportion of the second holding portion 62 inward. The folded backportions 61 a and 62 a are in contact with the substrates 11 of thefirst light source module 10 and the second light source module 20. Thefirst light source module 10 and the second light source module 20 areclamped in place by the folded back portions 61 a and 62 a.

(Light Source Unit According to First Modified Embodiment)

Next, a light source unit 1A according to the first modified embodimentof the present invention will be described using FIG. 16A and FIG. 16B.FIG. 16A and FIG. 16B are perspective views of the light source unitaccording to the first modified embodiment of the present invention.

The light source unit 1A according to the first modified embodimentdiffers from the light source unit 1 according to the above embodimentin regard to the configuration of the light source arrangement portionin the heat sink and the arrangement of the light source module. Itshould be noted that all other configurations are similar to the lightsource unit 1 according to the above embodiment, and as such,descriptions thereof are omitted.

As is illustrated in FIG. 16A and FIG. 16B, with the light source unit1A according to the first modified embodiment, the mounting surface ofthe light source module is inclined in such a manner that a light sourcearrangement portion 41A of a heat sink 40A gradually increases inthickness from the back to the front.

More specifically, the mounting surface (concave portion) of the firstlight source module 10 is included in such a manner that the thicknessof a first light source arrangement portion 41Aa gradually increasesfrom the back to the front. In other words, compared to the first lightsource arrangement portion 41 a according to the above embodiment, themounting surface of the first light source module 10 on the first lightsource arrangement portion 41Aa inclines so as to near the reflector 30.

Similarly, the mounting surface (concave portion) of the second lightsource module 20 is included in such a manner that the thickness of asecond light source arrangement portion 41Ab gradually increases fromthe back to the front. In other words, compared to the second lightsource arrangement portion 41 b according to the above embodiment, themounting surface of the second light source module 20 on the secondlight source arrangement portion 41Ab inclines so as to near thereflector 30.

With this, compared to the above embodiment, the first light sourcemodule 10 and the second light source module 20 are arranged inclined atan angle in such a manner that the front end of the substrate nears thereflector 30.

Next, an example of the functionality of the light source unit 1Aaccording to the first modified embodiment will be described using FIG.17A through FIG. 17C. FIG. 17A is for illustrating the ray paths oflight emitted from the first light source module in the light sourceunit according to an embodiment of the present invention, and FIG. 17Band FIG. 17C are for illustrating the ray paths of light emitted fromthe first light source module in the light source unit according to thefirst modified embodiment of the present invention.

It should be noted that in FIG. 17A through FIG. 17C, the arrows drawnwith solid lines indicate effective beams among the light emitted fromthe first light source module 10, and the arrows drawn with dashed linesrepresent null beams among the light emitted from the first light sourcemodule 10.

As is illustrated in FIG. 17A and FIG. 17B, when reflectors having thesame shape are used, in the case of the light source unit 1A accordingto the first modified embodiment, it is possible to reduce the nullbeams and increase the effective beams compared to the light source unit1 according to the above embodiment.

As a result, compared to the light source unit 1 according to the aboveembodiment, with the light source unit 1A according to the firstmodified embodiment, it is possible to increase brightness (improveperformance) or obtain the same degree of brightness while reducingpower consumption.

On the other hand, as is illustrated in FIG. 17A and FIG. 17C, if theeffective beams are to be equal, the length L of the reflector in thedepthwise direction can be reduced to make a more compact reflector,thus contributing to a more compact light source unit.

Moreover, as with the first modified embodiment, by arranging the firstlight source module 10 and the second light source module 20 on anincline, the light source component (the first light source module 10and the second light source module 20) becomes more difficult to viewdirectly, thereby reducing glare and a blinding effect.

(Light Source Unit According to Second Modified Embodiment)

Next, a light source unit 1B according to the second modified embodimentof the present invention will be described using FIG. 18A, FIG. 18B, andFIG. 19. FIG. 18A is a perspective view of the front of the light sourceunit according to the second modified embodiment of the presentinvention from above. FIG. 18B is a perspective view of the back of thelight source unit according to the second modified embodiment of thepresent invention from above. (a) in FIG. 19 is a front view of thelight source unit according to the second modified embodiment of thepresent invention, (b) in FIG. 19 is a top view of the same light sourceunit, (c) in FIG. 19 is a bottom view of the same light source unit, (d)in FIG. 19 is a left side view of the same light source unit, and (e) inFIG. 19 is a right side view of the same light source unit.

The light source unit 1B according to the second modified embodimentdiffers from the light source unit 1 according to the above embodimentin regard to the configuration of a reflector 30B and a light-blockingcomponent 50B. It should be noted that all other configurations aresimilar to the light source unit 1 according to the above embodiment,and as such, descriptions thereof are omitted.

As is illustrated in FIG. 18A, FIG. 18B, and FIG. 19, with the lightsource unit 1B according to the second modified embodiment, the upperportion of the reflector 30B extends further forward than thelight-blocking component 50B.

The light-blocking component 50B is configured to surround thelight-emitting units of the first light source module 10 and the secondlight source module 20, as is illustrated in FIG. 20A and FIG. 20B. Morespecifically, compared to the light-blocking component 50 according tothe above embodiment, the light-blocking component 50B includeslight-blocking walls 53 a which connect the side wall portions of theupper extension portion 51 b of the central portion 51 and the two upperextension portions 52 b of the side portions 52. Moreover, thelight-blocking component 50B includes light-blocking walls 53 b inpositions connecting the side wall portions of lower extension portion51 c of the central portion 51 and the lower extension portions 52 c ofthe side portions 52.

The light-blocking walls 53 a are configured to cover the sides of thelight-emitting unit of the first light source module 10. Thelight-blocking walls 53 b are configured to cover the sides of thelight-emitting unit of the second light source module 20. Thelight-blocking walls 53 a and 53 b are provided on the frontward portionof the side portions 52 (for example, half of the side portions 52), butare not provided on the rearward side (reflector side).

Moreover, the light-blocking component 50B according to the secondmodified embodiment includes lettering 54 a indicating directionality ona side wall 54 of the side portion 52. With this, when attaching thelight-blocking component 50B to the light source arrangement portion 41,the light-blocking component 50B can be attached without mixing up whichside is the top and which side is the bottom.

As is described above, in the second modified embodiment, the upperportion (top end portion) of the reflector 30B extends further forwardthan the light-blocking component 50B. This configuration makes itpossible to reduce glare resulting from light leaking in the upwarddirection.

Furthermore, the light-blocking component 50B according to the secondmodified embodiment includes light-blocking walls 53 a and 53 b inaddition to the upper extension portion 51 b and the lower extensionportion 51 c. With this, the light-emitting units of the first lightsource module 10 and the second light source module 20 are covered onthe sides by the light-blocking walls 53 a and 53 b in addition to onthe top and bottom by the upper extension portion 51 b and the lowerextension portion 51 c. This configuration makes it possible to reduceglare resulting from light leaking in the upward direction and from thesides.

Here, as is illustrated in FIG. 21, upon changing the orientation of thelight source unit 1B according to the second modified embodiment andtesting the light blocking effect (glare reducing effect) thereof, itwas found that glare can be reduced since the first light source module10 is practically non-visible from any angle. It should be noted that in(a) through (e) in FIG. 21, the orientation (angle) of the light sourceunit 1B varies in 30 degree intervals. As the 90 degree angle view fromabove ((c) in FIG. 21) illustrates, the first light source module 10 inthe stand-alone body of the light source unit 1B can be seen slightly,but when the light source unit 1B is mounted in the vehicle front lamp,the first light source module 10 is practically non-visible and theeffect of glare is virtually nonexistent.

(Vehicle Front Lamp)

Next, the vehicle front lamp 100 according to the embodiment of thepresent invention will be described using FIG. 22. FIG. 22 is asimplified cross-sectional view of the vehicle front lamp according toan embodiment of the present invention.

As is illustrated in FIG. 22, the vehicle front lamp 100 according tothe embodiment is a headlamp used in vehicles, such as two-wheeledvehicles or four-wheeled vehicles. The vehicle front lamp 100 includesthe light source unit 1, a housing 110 to which the light source unit 1is attached, and an optical component 120 arranged in front of the lightsource unit 1.

The housing 110 houses and retains the light source unit 1. For example,the housing 110 and the light source unit 1 can be fixed together byscrewing a screw inserted in the attachment hole 44 of the light sourceunit 1 into a screw hole provided in the housing 110. It should be notedthat the housing 110 may be configured of a plurality of components.

The optical component 120 is, for example, a headlamp cover (frontcover) that is transparent, and light emitted from the light source unit1 passes through the optical component 120 to the outside. Moreover, theoptical component 120 may have a light diffusing function or a lensfunction.

The inside of the vehicle front lamp 100 configured in this way ishermetically sealed, for example, to keep water or dust from entering.It should be noted that a separate reflector, for example, may also beincluded inside the vehicle front lamp 100 between the light source unit1 and the optical component 120.

In this way, the light source unit 1 can be used as the light source inthe vehicle front lamp 100. It should be noted that the light sourceunits 1A and 1B according to the first and second modified embodimentsmay be used as a substitute for the light source unit 1.

Other Modified Embodiments

The light source unit and the vehicle front lamp have herein beendescribed based on embodiments of the present invention, but the presentinvention is not limited to the above embodiments.

For example, in the above embodiment and modifications thereof, thepositioning of the reflector 30 and the heat sink 40 is determined bythe protruding portion (bulge) 34 provided on the reflector 30 and thesunken portion (depression) 42 a provided in the heat sink 40, butconversely the sunken portion (depression) may be provided in thereflector 30 and the protruding portion (bulge) may be provided on theheat sink 40 for determining the positioning. It should be noted that inorder to determine the relative positional relationship of the reflector30 and the heat sink 40, a protruding portion may be provided on one ofthe reflector 30 and the concave portion 42. In this case, theprotruding portion provided on one of the reflector 30 and the concaveportion 42 may be configured to extend toward and abut the other of thereflector 30 and the concave portion 42.

Moreover, in the above embodiment and modifications thereof, two lightsource modules—the first light source module 10 and the second lightsource module 20—are used as the light source components, but simply oneor the other may also be used.

Moreover, in the above embodiment and modifications thereof, a COBstructure LED module is used for the first light source module 10 andthe second light source module 20, but a surface mount device (SMD)structure LED module may be used. For example, as the SMD type LEDmodule, a package type LED elements (SMD type LED element), in which anLED chip (light-emitting element) is mounted in a cavity in a resincontainer and the cavity is sealed with a sealing component(phosphor-containing resin), may mounted on the substrate 11 inplurality.

Moreover, in the above embodiment and modifications thereof, aconfiguration in which white light is radiated using a yellow phosphoron a blue LED chip is used, but the present invention is not limited tothis example. For example, in order to increase color renderingproperties, in addition to the yellow phosphor, a red phosphor or agreen phosphor may be mixed in. Moreover, a configuration is possible inwhich, without using a yellow phosphor, a phosphor-containing resinwhich includes red and green phosphors is used and white light isradiated when used in combination with a blue LED chip.

Moreover, in the above embodiment and modifications thereof, a blue LEDchip is used, but an LED chip which emits light of a color other thanblue may be used. For example, when an LED chip which emits ultra-violetrays is used, a combination of phosphor particles which respectivelyemit the three primary colors (red, green and blue) can be used.Furthermore, wavelength converting materials other than phosphorparticles may be used. For example, materials including a substancewhich absorbs a certain wavelength of light and emits light of adifferent wavelength, such as semiconductors, metal complexes, organicdyes, and pigments, may be used.

Moreover, in the above embodiment and modifications thereof, thelight-emitting element is exemplified by an LED, but a semiconductorlight-emitting element such as a semiconductor laser, an electroluminescence (EL) element such as an organic EL element or an inorganicEL element, or other solid-state light-emitting elements may be used.

Moreover, in the above embodiment and modifications thereof, the lightsource unit is exemplified as being used in the vehicle front lamp usedin vehicles such as two-wheeled vehicles or four-wheeled vehicles, butthe present invention is not limited to this example. For example, thelight source unit may be applied to lighting equipment other than avehicle front lamp, such as lighting equipment used outdoors like a roadsign or billboard, or lighting equipment used indoors.

Although only some exemplary embodiments of the present invention havebeen described in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of the present invention. Accordingly, all such modificationsare intended to be included within the scope of the present invention.

The invention claimed is:
 1. A light source unit, comprising: a firstlight source module; a second light source module; and a light sourcearrangement portion between the first light source module and the secondlight source module, wherein the first light source module and thesecond light source module are staggered in at least one of afront-and-back direction and a left-and-right direction, the first lightsource module and the second light source module are arrangedsandwiching the light source arrangement portion from above and below,and the first light source module and the second light source module aredisposed in different positions in the left-and-right direction, whereinthe left-and-right direction is a direction perpendicular to both anup-and-down direction and the front-and-back direction.
 2. The lightsource unit according to claim 1, wherein the first light source moduleis positioned further forward than the second light source module. 3.The light source unit according to claim 1, wherein the first lightsource module is a low-beam light-emitting diode (LED) module, and thesecond light source module is a high-beam LED module.
 4. The lightsource unit according to claim 1, further comprising a reflector thatreflects light from the first light source module and the second lightsource module; and a light-blocking component that blocks a portion ofthe light emitted from at least one of the first light source module andthe second light source module and reflected off the reflector, thelight-blocking component blocking the portion of the light to form twopredetermined types of beam patterns, wherein the light-blockingcomponent has a surface that reduces light reflection.
 5. The lightsource unit according to claim 4, wherein the surface of thelight-blocking component is deglossed.
 6. The light source unitaccording to claim 4, wherein a reflection rate of visible light on thesurface of the light-blocking component is at least less than areflection rate of visible light on the reflector.
 7. The light sourceunit according to claim 4, wherein a surface roughness Ra of thelight-blocking component is at least 0.5 μm.
 8. The light source unitaccording to claim 4, further comprising a heat sink, wherein the lightsource arrangement portion is formed as a portion of the heat sinkextending therefrom, and the light-blocking component is attached to thelight source arrangement portion and positioned in front of the firstlight source module and the second light source module.
 9. The lightsource unit according to claim 4, wherein the light-blocking componentforms a cut-off line.